Buckingham St. In the Strand, London. Margate.
Suzannah Foad from Isle of Thanet list says he is listed in the London & County directory of 1811 as solicitor, in the High Street Margate.

His Niece Sarah Was His Executor And Beneficiary. Newspaper sheet in family archive about his death.
age 60 on burial (copyin file)

Suzannah Foad from Isle of Thanet list says he is listed in the London & County directory of 1811 as solicitor, in the High Street Margate. She says there is a John Chapman & wife Eliza on a headstone in St John in Thanet whose son John was buried in 18 june 1849 age 56. She also looked at the Overseers Rates for St John Margate. the entries from 1804-1814. It was taken Quarterly and Thomas had a House, Cottages and Stables in the High Street. Thomas lived near the Barracks so would have been at the top of the High Street near the Six Bells and St John's Church Jan 1804 he was paying rents on 8 properties at a total of 12 shillings until April 1804 when he had 12 Rents and at a Total of 12 shillings, this carried on until March 1814.
 (The Rev William Chapman had 40 Properties!) 

Bond dated 12 May 1809 between Thomas Chapman and Peter Upsdell, is to make Peter Upsdell make good the faults he had made in repairing the rrof of 19 Buckingham St in the Strand, owned by Thomas, in occupation opf William Young. (F/18 and transcription J/c/16)

There is also a Deed of Covenant on Thomas dated 8 Oct 1794 to produce title deeds for 3 others. (F/17 and transcription J/c/17)

Information about 19 Buckingham Street : There were originally two houses on the site, both of which were burnt down. The present building was erected in 1894 and let in chambers by Peter Bogue. W H W Betty the actor lived there 1817 - 20