Swell Tor quarry is one of a whole group of quarries located near Princetown and Tavistock in west Devon that includes Foggintor, Kings Tor, Crip Tor and Merrivale and a quarry near to the prison in Princetown. Granite from Dartmoor was used in many places. Near to the Swell Tor quarry there are still twelve corbels carved for (the old) London Bridge for the purposes of widening in 1902.  There are also the remains of the blacksmith's workshop and traces of the railway.
Swell Tor was one of the larger quarries in the area and was operational until the early 20th century. Stone from it was used for the Thames Embankment (1846-47), Alexander Binnie's new bridge at Vauxhall in London (1903) and the Bristol Waterworks (1902).  Although employing up to 90 men before the First World War it closed in the 1920s. It briefly re-opened in 1937, but after 1938 it has not seen any major workings. 
 BBC Devon Walks: Princetown to King's Tor http://www.bbc.co.uk/devon/content/articles/2005/09/13/princetown_railway_walk.shtml
 John Watson, 'British and Foreign Building Stones: A Descriptive Catalogue of the Specimens in the Sedgwick Museum, Cambridge', 1911, Cambridge University Press, Cambridge p.18
 Kath Brewer, 'The Railways, Quarries and Cottages of Foggintor', 1997, Orchard Publications, Newton Abbott, p.58