Many accurate 1921 census transcriptions have already been added to the pub history site, including London, and parts of Middlesex. If you can contribute to the site, send me some details to Kevan, along with some description of the specific property.
Directory of Pubs in the UK, historical public houses, Taverns, Inns, Beer Houses and Hotels in Hertfordshire . The Hertfordshire listing uses information from census, Trade Directories and History to add licensees, bar staff, Lodgers and Visitors.
The John Carey Road Map of London to Hertfordshire - in 1790
**** Provided By Kevan