Who was Benham? So far it has proved impossible to find out from the Internet as any attempt at Googling Benham+Hampstead just brings up endless links related to local estate agents Benham and Reeves (and since it appears they weren't established until 1958 it's unlikely to be anything to do with them).

Update - persistence pays off. He was a high street grocer.
"Benham's Place, nine terraced cottages built in 1813 by William Benham, a High Street grocer"
British History Online