The site had been formally occupied by Crescent House, which had been inhabited by the former Governor of the Bank of England Edward Howley Palmer, since 1881.
[6] The Survey of London felt that Mortimer House "...exudes an air of mystery and surprise amid the surrounding terraces of South Kensington".
[1][7] The house is built in the late 19th-century Tudorbethan style in red and blue interspersed brickwork, with various decorations including gables and statues of griffins and bears with shields.
The Survey of London described the interior as having "...a predictable eclecticism of style, ranging from Jacobean in the long hallway containing an oak open-well staircase with twisted balusters and wide handrail to Adamesque in the double drawing-room at the front.
"[1] The London: North edition of the Pevsner Architectural Guides describes Mortimer House as "a picturesque composition", highlighting its "Tudor chimneys with crenelated pots and stone mullions".