St Michael's Mount (Cornish: Karrek Loos yn Koos, meaning "hoar rock in woodland", also known colloquially by locals as simply The Mount) is a tidal island 366 m (400 yd) off the Mount's Bay coast of Cornwall, England. It is a civil parish and is united with the town of Marazion by a man-made causeway of granite setts, passable between mid-tide and low water. St. Michael's Mount is one of 43 (unbridged) tidal islands which can be walked to from mainland Britain.
Little is known about the village before the beginning of 18th century, save that there were a few fishermen's cottages and monastic cottages. After improvements to the harbour in 1727, St Michael's Mount became a flourishing seaport, and by 1811 there were 53 houses and four streets. The pier was extended in 1821 and the population peaked in the same year, when the island had 221 people. There were three schools, a Wesleyan chapel, and three public houses, mostly used by visiting sailors. The village went into decline following major improvements to nearby Penzance harbour and the extension of the railway to Penzance in 1852, and many of the houses and buildings were demolished.
Until recent times both the Mount and the town of Marazion formed part of the parish of St. Hilary. [NOTE: A Vision of Britain through Time gives no date for this arrangement.] St Michael's Mount was part of the West Penwith Rural District from 1894 until 1974.
One of the many maps available on A Vision of Britain through Time is one from the Ordnance Survey Series of 1900 illustrating the parish boundaries of Cornwall at the turn of the 20th century. This map blows up to show all the parishes and many of the small villages and hamlets.
The following websites have pages explaining their provisions in WeRelate's Repository Section. Some provide free online databases.