Home » Sunken Lancashire
These include a number of the so-called "Lost Villages of Muchland" which were believed by antiquarians to have been washed away, though more likely were not, simply being abandoned or renamed, and other places such as Singleton Thorp and Waddum Thorp which almost certainly never existed. There are, however, documentary records for other locales - Kilgrimol, Argarmeles and Aynesdale - which state categorically that they were lost to the sea, while others, most notably Old Formby, were covered over by the sand.
This page collects details on these and other places known to have suffered the effects of flooding along this county's coastline and adjacent areas.
The village of Argarmeles or Argarmeols, which was probably situatied close to the present-day Birkdale, appears in the Domesday Book as Erengermeles. By 1248, Thomas de Betham held lands at Argarmell at his demise. Later that century, Roger de Argarmeles held lands stretching along the coast as far as Old Formby.
By the mid-14th century, parts of Argarmeles had come into the possession of the Halsall family: the settlement was "now annihilate by the sea and there is no habitation there." The place is mentioned in a 1377 agreement between Otes and William de Aughton alongside Ainsale and Birkdale, with the precise boundaries of each left unexplained. A later statement to the effect that "Thomas de Beetham and his parceners" held the fourth part of a knight's fee in Argar Meols may be anachronistic.
In 1503, Sir Henry Halsall was charged rent by Henry VII for lands at Argarmeles, though he claimed that, long before his father's time, Argarmeles was "within the hegh see and drowned and adnihilate with the sayd see, and oute off the lawgh water marke, and also oute of the bodye of the said countye." Corroborating this claim was the testimony of a John Shirlok, born in 1423, who stated that he had "hard sey that suche londes ther were and drowned in the See but wher ne in what parte he never hard tell."
The 16th May 1553 saw an incident on the dunes south of today's seaside settlement of Southport, in which it is alleged that a group of men, led by Edmonde Holme, broke into a house at a place called Menedale, taking the tenant, Thomas Rymor, hostage. Holme's reasons for his actions were the alleged encroachment on his holdings at Anoldesdall, which had been in his family for well over a century, by Henry Halsall, the lord of Birkdale to the north. As such, he dispatched his servants to pull down the frame of a house built on lands which he made use of for the purposes of fishing. Halsall alleged that there was no such manor, but he had heard of the similarly-named Aynesdale, "near adjoining the said 600 acres of land called Meanedale" which had "time out of mind has been and is still 'overflowen' with the sea so that there remains no remembrance thereof now."
Indeed, a township named Aynesdale (I use this spelling to disassociate it from its modern successor Ainsdale) features heavily in charters à propos Cockersand Abbey and its holdings from 1190 to 1279, which name a variety of landholders and some twenty or so toponyms. Whether or not Halsall was exaggerating (we may remember that it was his grandfather of the same name who opined that the township of Argarmelys, for which he was sued by the crown for rents due, had long since been washed away) seems a moot point, given that the Holmes' activities in the area seem to have been much more restricted in scale and land use than those recorded in the Cockersand charters. Also, given the diminution of Raven Meols to the south and the reports about Argarmeles, a scenario in which the once-thriving settlement of Aynesdale fell pray to the waves is by no means impossible.
The Cockersand grants show that, during the period around AD 1200, a good deal of land in the region was under the plough. Slightly later, in the 13th century, land reclamation was underway: the monks are given an area of marsh and mossland between Siward's Croft and Blakemere on the proviso that they remove the sand in the area. Names which appear frequently in the charters include field names such as Atefield, located in or near the Wray (which also features in Formby land grants), hillocks (Melcanrehow, Alserhow, Halsteadhow, Bradehow and Gripknots) and valleys (Romsdale, Whitemeoldale). A second settlement perhaps is West Ainsdale, treated separately in the charters. Previous landowners show a propensity for names derived from Old Norse: these include Odd (attested in the place name Lesser Oddasargh), Orm Dragun, Ravenkil, Toki and Siward. At least two men bearing the name Ughtred, which has a significant northern pedigree, also appear. Perhaps significantly, Birkdale (as well as Birchdene and Kirkdale) also feature in the charters, which also suggest a border between Formby (possibly separate from Aynesdale) and Argarmeles.
The idea of certain villages mentioned in the Domesday Book and later sources within south west Furness being lost to the waves is first suggested by an early historian of the area, Thomas West, in the 18th century. Subsequently, a number of studies have weighed in on the subject, proposing locations for the villages ranging from the improbable (the Leven estuary off Ulverston) to the far more reasonable, and it seems unlikely that all - if any - of the settlements - particularly Fordebodele, Hert and Cliverton/Crivelton - lay on or off the coast.
At the time of the Domesday survey, the region formed part of the Manor of Hougun (perhaps based at Millom in Cumberland or at High Haume), which had belonged to the Saxon rebel Tostig prior to the Norman Conquest. This manor included a number of settlements, including Fordebodele, Hert, Lies, Alia Lies and Crivelton.
Local legends recall that the Furness village of Aldingham was once much larger than it is today, up to a mile long, with the church of St. Cuthbert - currently on the very edge of the land - at its centre. Interestingly, Aldingham Scar and Church Scar lie east of the present-day village towards the Leven estuary.
Perhaps associated with this lore is the alleged village of Low Scales, which was said to have been visible at some point during the 18th century. The village of Scales lies north-west of Aldingham, thus it is possible to speculate a connection between these names. The appearance of these remains suggests a measure of truth to this legend.
The bells of Kilgrimol priory are reputed to still sound beneath the waves lapping the sand dunes at St. Anne's-on-Sea. This romantic-sounding name is genuine: it appears in an 1199 land grant made by Richard Fitz Roger (who raised a cross there) to the monks of Durham, and in the early 1270s, when Ranulf de Dacre declared it common for Lytham and Layton. Kilgrimol appears in a dispute between the Prior of Lytham and Sibyl, widow of William Boteler, dating to about 1338, in which the Prior alleged that Sibyl had "seized an anchor at Kelgrimoll (at Greenskar pot)," whilst Sibyl maintained that it was taken in her domains at Great Layton.
The name and nature of Kilgrimol as it appears in early sources has led to a good deal of speculation that the first element is suggestive of the presence of Culdees, a movement of ascetic monks whose origins lie in Ireland. Eilert Ekwall, however, suggests that the name actually means the hol (or "hollow") of one Kelgrim, a name which also appears in the name of Kellamergh - "Kelgrim's argh or summer pasture," to the north east of Lytham. Ekwall notes a suggestion by Björkman that the name commemorates one *Ketilgrimr, though dismisses it: the name Ketil appears in placenames in the adjoining township of Marton (Ketelsworth, Kettlesholmewathwra). The place was presumably situated in low-lying land beneath the present-day dunes, with raised ground on either side: the later names of farmsteads, Stony Hill to the north east and Twiggy Hill to the south east, as well as the area known as Cross Slack - which is strongly associated with the Kilgrimol cross - bear this topography out.
The church at Kilgrimol was undoubtedly ancient, the cemetery being named in Richard Fitz Roger's original grant. Richard's cross near the cemetery, which may be the old cross on Croshowe mentioned in the 13th century (though the various crosses on the sand hills became the foundations of boundary disputes centuries later). The church was located on an expanse of dunes stretching down from the coast at modern-day Blackpool around the northern side of the opening of the Ribble estuary towards Lytham. On the west lay the sea, ever lapping at the foundations of the dunes, always with the threat and promise of an overwhelming swell. Immediately to the east of Kilgrimol stood the foetid, brackish waters of the ominously-named Cursed Mere, a region of treacherous standing water within the wide expanse of mossland separated from the ocean by the narrow finger of sand where the ancient church stood, and one which has, over the course of the centuries, claimed the lives of many unwary kine.
The story its inundation also has a venerable age: John Bochier, 72 years old in 1532, was called as a witness at a Duchy court proceeding brought by the Prior of Lytham and recalled that he had heard that "Kelgrymoles churchyard" had "worne into the sea two or three miles," testimony corroborated by one Robert Crokay, who stated that, during the lifetime of his father, then aged 94, some two to three miles of pasture had "worn into the sea." Thus, Kilgrimol appears to have fallen prey to the waves at the transition from the Medieval Warm Period to the Little Ice Age (as did certain villages to the south). The churchyard and cross are remembered in the name Cross Slack (earlier Churchyard Slack), which came to be sparsely inhabited during the 16th or 17th century. Interestingly, Henry VIII's decision on the 1532 case mentions "common and waste ground in [...] Kylgremosse," a subtly different variant on the name which may indicate the veracity of the tradition, with the former site becoming inundated and later forming part of the mossland. The precise mechanism by which Kilgrimol fell prey to the sea is perhaps similar to that of 1927, when "the tide broke through the sandhills on North Drive and flooded the road to a depth of six feet" at the later settlement of St. Anne's-on-Sea.
Kilgrimol is also mentioned in testimonies dating to 1608, with a number of witnesses confirming the previous statements that it had been lain waste by the sea. In particular, one Richard Fishe of Lytham, a man of about 70 years of aged in 1608, adds some interesting details: -
And he further saith that he knoweth a place in the Hawes called Churchyard Slack, and that he hath seene great stones or ground work of walls under full sea within flood water west from Churchyard Slack and he thinketh that the Church of Killgramoll stood there.
The precise location of the Kilgrimol cross was apparently lost, with testimonies in the 1532 and 1608 cases musing on the identification (or otherwise) with Richard Fitz Roger's cross of a number of others located in the area. These were the wooden cross with a statue of St. Cuthbert destroyed by Boteler's men, and the Cross-in-the-Hawes, which Robert Crokay's father said: -
[W]as first set up for a remembrance that one Fideler killed a man called Wheler, and 'nawther for meyre ner bounde.'
Kilgrimol, of course, also piqued the fancy of literary-minded sorts in Victorian England, which no doubt fed the legend. Rev. W.T. Bulpit, writing in 1879, suggests that "evil spirits," worshipped by the Britons, lurked "in the water marshes around Marton Mere," until "Grim, the priest from Kilgrimol [...] cast the chief spirit into the mere," where it took on the shape of "a great worm or conger eel." Later, in Viking times, "the eel was loose and came out to the dwellings of those who took refuge on the shore, and ate sheep and even children," and the ministrations of the local clergyman proved ineffectual against it, "and so he went to Cross Slack, where Grim’s oratory had stood, and hoped Grim would aid him by a vision." Subsequently, as "Grim’s little bell rang for Prime," the priest heard a voice which gave him directions for dealing with the beast, who was henceforth confined to Marton Mere... "and even yet, on a moonlit night, a swell on the water marks where he rolls in agony." William Canton gave another acount in a volume entitled A Child's Book of Saints, which recounts the tale of Oswald the Gentle, supposed Prior of Kilgrimol, in "the ancient years before the great inroad of the sea which broke down the high firs of the western forest of Amounderness, and left behind it those tracts of sand and shingle that are now called the Blowing Sands." Canton places Oswald's career and the destruction of Kilgrimol prior to the Black Death (which hit this part of England in 1349). Oswald's name, however, and that of the other characters Anselm and Bede, point to Anglo-Saxon times. Canton also made extensive use of the tidings of Kilgrimol and Waddum Thorp in his Queen Mab.
Perhaps the best thing to finish up on is Clive Kirsten's notice, a humorous take on the legend of the ghostly bells: -
The legend has it that the bells of Kilgrimol church (or oratory) can be heard sound beneath the waves on stormy nights. This is such a repeated assertion that locals will avow that it must be true. But that is like believing Tony Blair's repeated claim that the Iraqi military had weapons of mass destruction.
Waddum Thorp's first appearance in print was in Peter Whittle's Marina in 1831, where he supposedly quotes Roger Dodsworth as saying that "[t]hree miles from Lytham, there is a place called cross slack, or church yard slack; at this spot a thorp of village existed, so late as the year 1601; titled or known by the name of 'Waddum Thorp.' The horse-bank, below Lytham, was originally a pasturage for cattle - even in the year 1612; during the reign of James First." This is backed up by a quote from Dr. Charles Leigh, stating that "Waddum Thorp existed as a village, so late as the year 1601; and, during the Saxon era, formed habitations for fishermen and others, on that line of coast. Cross-slack was originally termed 'Church-yard-slack,' from there having been a religious oratory, and cemetery there."
These evidences are problematic: firstly, "Dodsworth"'s Waddum Thorp is located where the real hamlet or chapel of Kilgrimol was, while "Leigh"'s reference is to Lytham (according to the more sober-minded Thomas Baines and Brooke Herford). Additionally, the Horse Bank appears on maps only in the early 19th century, when Greenwood depicts it in his 1818 map Brazier's chart of 1820 places "Horse Sand" at the mouth of the River Ribble. By 1850, the Horse Bank had increased its extent to the south, where it is currently placed. Additionally, while the statement about Cross Slack formerly being known by the name of Churchyard Slack is almost certainly correct (Churchyard Slack appears in 1608 for example), such a detail is likely anachronistic.
Like the story of Waddum Thorp, Peter Whittle is the earliest source for the statement that: "[t]he horse-bank, below Lytham, was originally a pasturage for cattle - even in the year 1612; during the reign of James First."
Whittle, or his informant(s), likely took this idea from earlier reports of the washing away of Kilgrimol: in 1532, Robert Crokay of Warbreck reported that, during the lifetime of his 94-year-old father, some two to three miles of pasture had worn into the sea.
The earliest evidence for the name of the Horse Bank dates from considerably later than 1612. While William Ashton states that a chart dating from 1809 depicts the Horse Bank as "mostly water, dotted with eight small islands," it is unclear whether the said chart named this area as the such or whether this was the name by which Ashton knew it. Greenwood's map of 1818 shows the Horse Bank as the westernmost sandbank in the Ribble estuary, with Salter's Bank to the north and Packington Flatt and Packington Bank to the south. Subsequently, Brazier's chart of 1820-1824 displays the "Horse Sand" in the same area. The Horse Bank gradually migrates southward through the course of the 19th century, into its present location off the coast at Southport.
Of the earlier charts, Fearon and Eyes place Stevens Wharf off the Kilgrimol coast, with the Butter Wharf lying south west of it. Dawsons Bank is further up the estuary, while Packington appears in the area where Greenwood put the Horse Bank. By the time of Mackenzie, in 1761, Stevens Wharf has become the South Bank, while the Butter Wharf covers much of the area formerly known as Packington: this latter name is applied to an area of sand to the south and south west, where Greenwood would locate Packington Bank.
Singleton Thorp first appears in print in Peter Whittle's Marina, before Rev. William Thornber took the idea and developed it in both his historical work and in fiction. The legend appears to be primarily an outgrowth of a tradition which held that the Penny Stone, a boulder located off the coast west of Norbreck, had formerly formed part of an inn, the ghostly revellers in which might still be heard. Whittle claimed to have found a report in the extensive manuscripts written by the prolific Roger Dodsworth to "a sudden irruption of the sea," which "took place at Rossal grange, - the sea washed in a whole village, called Singleton Thorp. The inhabitants were obliged to flee from the ancient spot, and erected their tents at the place, called Singleton to this day." This is, of course, fanciful: Singleton Thorp is unattested prior to Whittle's supposed discoveries, and the inland village of Singleton certainly dates to a period well before the 1550s, appearing in sources throughout medieval times. Nevertheless, remains of what appear to be buildings have been found off the coast. Alfred Halstead interpreted sundry discoveries found in 1893 as the roof beam of a house and rubble wall foundation, while Wyre Archaeology Group members reported finding wooden and stone features about a third of a mile south of Rossall School.
By 1845, in his Penny Stone, Rev. Thornber has Singleton Thorp "situated in a vale, protected from the sea by a barrier of sand hills at a short distance from a village named Singleton Thorp, in the Foreland of the Fylde, Lancashire. The site of the homestead was romantic, for it was in the very centre of a Druidical circle," while the Higher and Lower Gingle stones on the foreshore have given a name to "Higher Gingle-hall, the ancient residence of the Singletons." Additionally, the destruction of the settlement has now been backdated to 1588, in order to coincide with the scattering of the Spanish Armada: this soon became the "traditional" date.
The Higher and Lower Gingle, along with the Penny Stone, are of a number of large boulders which dotted the foreshore (some remain in place), the most significant of which is the Carlin Stone, which has a number of satellites (collectively, these are known as Carlin and the Colts). Thornber also names the "Silkstone, Bear and Staff, and the Coup off Blackpool," as well as Old Mother's Head, which lay off some way to the west of the Penny Stone. These rocks were deposited by the wearing away of the cliffs by the sea over many centuries.
According to Thornber, "Sir Richard de Singleton [...] eventually retired to Whittingham, in the parish of Kirkham, and there erected two mansions which he named Higher and Lower Gingle, in memory of his late residence near Singleton Thorp," adding as a melancholy detail: -
Tradition says, that he was the old man, who once a year, on the anniversary of the destruction of his ancient home, was wont in slow and melancholy steps to walk three times round Singleton Skeer, the site of his Thorp of that name, and to weep over two stones, known even now by the fishermen as Higher and Lower Gingle.
In reality, Chingle Hall was originally built by Adam de Singleton around 1260 and was in the hands of the family for over three centuries thereafter. It left the hands of the Singletons in 1585, when the ill-starred heiress Eleanor Singleton died. Eleanor has her own tragic backstory, which accords well with tales of the numerous hauntings reported in the hall.
A great storm devastates land in and around Walney Island and the west coast of Furness and beyond on 6th December 1553, leading to a commission being dispatched to assess the damage.
In 1733, the Lancaster-based Quaker businessman William Stout wrote his memoirs, in which he recalled his childhood on the Great Marsh, which extended: -
[H]alf way westward from our house to Presceare, and from Bare in the south, round about the Know End in Lindeth, to Arnsid-well, except a narrow inlet for the tide in Kear, but not sufficient to receive any boat or barque of burthen.
In 1677, when Stout was about 13: -
[T]he sea began to break into our marsh at the south end, next Bare, the river Kent then running very nigh Presceare [Priest's Carr] on the west and south side, and came upon the marsh with a breast, five or six yards deep, and undermined the marsh some yards," while, a decade later, "the sea continually wasted their marsh and Kear, which used to run near Lindeth, now drew towards Boulton Holmes, and to within Prescear, and also drew in the main river Kent, so that all the marsh to the west and north of us was washed away.
The effects of this shift was felt on the other side of the Kent estuary: when the Great Marsh vanished, says Stout: -
[T]here rose a marsh of some hundred acres at Winder Moor, at the south and west of Cartmel, to the great benefit of that part, and to the great loss of Boulton and Warton, from the year 1678.
Incidentally, the Rev. T.D. Whitaker, paraphrasing Mr. Lucas, the historian of Warton, notes a very strange and portentious occurrence in the region:-
After the precipitation of one of these great masses of sand into the stream in the latter end of the last century but one," i.e. the 17th, "some persons on the opposite side of the Ea" (which Whitaker explains as a term used for the estuary of the Kent) "observed the entire figure of a man on horseback, with his right hand elevated in the act of whipping his horse, in order to stimulate the sinking animal to extricate himself by a plunge. The whip was actually remaining in the rider's hand, and neither of the bodies, such were the effects of sea salt, had undergone any change from putrefaction.
Old Rossall appears on Fearon and Eyes' chart from 1737 on the coast to the north west of Rossall Hall (nowadays Rossall School). It is located on an area of land westward of the present coastline and is presumably included as a landmark, abandoned and in the process of being demolished by the encroaching sea. Four years previously, the Rossall estate had come into the hands of the Hesketh family. Prior to the Heskeths, the Fleetwood family held Rossall from the time of the Dissolution of the Monasteries. At that time, the Allen family has holdings in the area, as tenants of Dieulacres Abbey: their most famous member was Cardinal William Allen, the Catholic bugbear of Elizabeth I, who was born at Rossall in 1532. His kinsmen were evicted by Edmund Fleetwood after the death of his father Thomas in 1570, at which point Thomas held much of this part of the Fylde coast: -
Northbreke maner', Litle Bispham maner', Grete Byspham maner', Chornet, Rossall graungia, Pulton, [...] Rotherholme Magna maner', [...] Laton Magna maner', Laton Parva, Pole, [...] Werbrecke, Marton Magna, Norcrosse.
Of these places, Rotherholme Magna is perhaps Ritherham, modern Cleveleys, while William Ashton suspected that Chornet was "possibly [...] swallowed up by the sea's advance." Rossall Grange (associated with Singleton Thorp in "Dodsworth") was - by the mid-19th century - further north, on the western side of present-day Fleetwood. This was likely a reapplication of the name: Greenwood's map of 1818 and Hennet's of 1829 call this place "West Warren House." Roman coins were discovered on the coast west of this location in about 1840, leading to speculation that Ptolemy's Portus Setantiorum was located nearby (this was most likely on the other side of the peninsula, in the region of Burn Naze, formerly known as Bergerode). Carr House Farm, then the workplace of Peter Sykes, suffered losses when the sea broke through the embankment during heavy storms on the 25th and 27th December 1852.
Rev. William Thornber adds a further detail about the encroachments of the tide in this region: -
Our old people often relate, that their fathers were wont to say, that the sea was peaceable in their days; and a particular Sunday, about 72-3 years ago [i.e. around 1765], is named, when, owing to a change of current caused by the bursting of some sandbank, or by an elevation of the bottom of the sea, or some other unknown submarine catastrophe, the whole neighbourhood was alarmed at the immense body of water which advanced to the shore at the influx of the tide.
As an aside, a Glasson aphorism, "That's Rossall's wife churning," denoted the expected onset of a sou'westerly gale.
John Porter, the historian of the Fylde, records that Fenny, a farm at Rossall, "was removed back from threatened destruction by the waves at least four times within the last fifty years [Porter was writing in 1876], when its re-building was abandoned, and its site soon swept over by the billows."
The 17th century also saw the development of a thriving settlement at "Old Formby," which itself was gradually buried by the dunes between 1750 and 1850. John Formby, a local landowner and historian, describes it in the following terms: "[a]bout 1711 there was a fishing hamlet and a pier which is said to have stood some 600 yards north-west of the present St. Luke's Church. (It was Canon Hume, I think, who placed it here). I have it at second-hand from the Rev. Robert Cort that his old friend, when a boy, saw the troops embark at Formby pier, to go to quell the rebellion in Scotland. Now this must have been in the 1715, not the '45 rising, for in the 'thirties of the 18th century the place was destroyed by sand. I have heard that there was a great discussion whether the Docks should be built at Liverpool or Formby about 1700." Ashton adds the following account of its situation: "[t]radition supports the contention that the old port and town stood on the edge of a channel beyond which lay a long tidal-covered sandbank. The channel was beginning, about 1700, to silt up at the north end, precisely as the Southport to Lytham Channel began to choke up about 1880, and as the north channel by St. Annes filled up. The decline of the old port dates from this time, as the bank gradually joined up to the mainland. Mersey deposits would here again be the probable cause of the silting." Further evidence comes from the relation of Rev. Cort's informant in the last years of the 18th century, who was "said to have been the last inhabitant of the deserted town." He dwelt in the vicinity of the old cemetery by St. Luke's Church and recalled sporting as a boy by jumping from the pier onto the decks of the ships at harbour. During the early 19th century, according to the testimony of one Dr. Sumner, who died aged 84 in 1883, "there were evidences as to what is now the Altcar Rifle Range having been the site of a harbour in which large boats rode," and he remembered large vessels navigating up the Alt at that time, before its course turned southwards.
The 75-year-old Halsall man Hugh Tokwold, called as a witness at the 1503 proceedings against Sir Henry Halsall for tax evasion vis-á-vis Argarmeles, stated that he had "heard that the Abbots of Meryvall and Whalley had great lands within 4 miles of Halsall 'worn into the see.'" These two foundations had of long standing held lands around the Alt in Raven Meols. This particular manor represents a good example of the effects of encroachments by sea and sand: at the time of the Domesday survey, "Meles" was assessed as half a hide, which William Ashton translates to 24 oxgangs. By 1289, this area had been reduced by a half. By 1565, only one house remained in the manor, the remainder having fallen prey to encroaching sands.
As Raven Meols was abandoned, a new settlement, perhaps located on the opposite, southern bank of the Alt estuary, comes into view. William Camden notes that: "[n]eere unto Sefton, Alt a little river seeketh a way into the Sea, and when he hath found it, giveth name to a small village Altmouth standing by, and hath Ferneby nere unto it, wherein the moist and mossie soile turffes are digged up, which serve the inhabitants for fewell and candle light." Altmouth subsequently appears on maps until 1789. William Ashton's suggested identification with Moorhouses, a toponym appearing in the coucher book of Whalley Abbey and deeds associated with the Crosby and Blundell families, seems far-fetched.
James Stockdale, the son of another James, who bought the West Plains estate on the southern edges of the Cartmel peninsula, recalls the events of 1828, which saw the breaching of the Winder Low Marsh Embankment and inundation of the estate, which, he continues, was put down by many (including the 1851 Ordnance Survey map) as an inroad of the sea. Stockdale, however, names as the culprit the River Leven, which changed its lower course eastward, undermining the sandbanks: -
About the year 1827, it became apparent that the river Leven, which had taken its course beyond the memory of man, on the Bardsea side of the Ulverstone estuary, was gradually moving through the sandbanks towards the embankment at the Winder Low Marsh, and that in all probability it would soon re-occupy the course which from tradition it was known to have occupied about one hundred years before. On the 29th of July, 1828, the river had advanced so far through the sandbanks that the nearest part (of the river) was only 410 yards distant from the most westerly point of the Winder Low Marsh Embankment. At this time it approached the embankment nearly in the form of an immense segment of a circle, the arc being about two and a half to three miles, and the break or precipice all along the course of the river being about twenty feet in height. The water-edge, or margin of the river, particularly at the flow of the tide, sawed away and undermined the soft sandbanks, and caused them to fall with a tremendous plunge here and there all long the edge of this segment of a circle of two and a half to three miles, in immense masses, each of not less than twenty yards in length, eight or ten yards in width, and twenty feet in height, into the river beneath, with a continuous roar like the firing of heavy guns from a fort, or the noise of loud thunder. On the 26th October, the first or lowest row of sods of the embankment fell into the river, so that between the 29th of July and the 26th of October the river had passed through a sandbank four hundred and ten yards in width, two and a half to three miles in length, and twenty feet in height, and taken the whole mass in a suspended state in the water, into other parts of the estuary. [...] From this time the sea flowed again over the West Plain estate, and has continued to do so ever since.
Further information on areas prone to rising sea levels can be found on Climate Central's flood level projection map: -