In 1887, John Bartholomew's Gazetteer of the British Isles described Mayfair like this:
St George Hanover Square, par., Middlesex, in W. of London, 1119 ac., pop. 89,573; forms the Hanover Square parl. div. of Westminster.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Mayfair has changed, please see our redistricted information for the modern district of Westminster. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Mayfair and units named after it.
GB Historical GIS / University of Portsmouth, History of Mayfair, in Westminster and Middlesex | Map and description, A Vision of Britain through Time.
Date accessed: 27th May 2015
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Mayfair".