A Dewey is a hill or mountain in England or Wales over 500 metres (1,640 feet) in elevation, but below 2,000 feet (609.6 metres), with a relative height of at least 30 metres (98 feet). The list was compiled by Michael Dewey and published in his book Mountain Tables.
There have many changes to the original list resulting from remapping and surveying. As of 15 December 2013, 57 new hills have been added, 14 have been deleted, 3 replaced by a neighbouring summit, and 4 relocated to a significantly different grid reference