Spencer House is a historic mansion located at 27 St James's Place in the St James's area of London, England. The house is Grade I listed on the National Heritage List for England.
 
The house was commissioned in 1756 by John Spencer (who later became the first Earl Spencer), as he required a large townhouse in London to augment his position and status. The architect he chose was John Vardy, who had studied under William Kent. Vardy is responsible for the facades of the mansion that we see today.
 
Interesting fact...
The house also served as a temporary refuge in 1922 for the exiled Prince Andrew of Greece, his wife Princess Alice of Battenberg, and their infant son—future Duke of Edinburgh, Prince Philip who was later to marry the princess just next door!