Tresco (Cornish: Enys Skaw, meaning "island of elder-trees") is the second-biggest island of the Isles of Scilly in Cornwall, England. It is 297 hectares (1.15 sq mi) in size, measuring about 3.5 kilometres (2.2 mi) by 1.75 kilometres (1.09 mi).
The island is administered for the crown by the Duchy of Cornwall and is leased to the Dorrien-Smith estate, which runs it as a timeshare business. The Dorrien-Smith family (descended from Augustus Smith) held the position of Lord Proprietors of the Scilly Islands between 1834 and 1920.
The main habitations are the villages of New Grimsby and Old Grimsby in central part of the island. It is also the location of Tresco Abbey.
For more information, see the EN Wikipedia article Tresco, Cornwall.
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.