Spencer House, London

Private
Spencer House is one of the few surviving eighteenth-century grand London town houses, and almost the only one to retain its eighteenth-century interiors. Eight state rooms have been restored in the last ten years for RIT Capital Partners plc. Fireplaces, architraves, doors etc have been replaced to restore the full splendour of the house’s late eighteenth-century appearance.
This private palace was built in 1756-66 for the first Earl Spencer, an ancestor of the late Diana, Princess of Wales. Money was clearly no object. The exterior, by architect John Vardy, is in a Palladian style, and the interiors were designed by John Vardy and James ‘Athenian’ Stuart.
The ground floor has the entrance hall, Morning Room, Ante-room (with apsidal alcove) the Library, the Dining Room (with scagliola pillars) and the astonishing Palm Room.
Ascending via the Staircase Hall one finds the Music Room, Lady Spencer’s Room, the Great Room (aptly named, with curved, coffered and highly decorated ceiling) and the Roman-styled Painted Room.
The State Rooms have the original ceilings, generally highly ornate, and restored and very ornate fireplaces and woodwork. There is lots of gold-leaf gilding. The Palm Room has an unique palm tree design with gilded trunks.
The interior is really worth seeing. Furniture represents what was originally here, and a few pieces are the originals, returned to their original positions. There are also interesting paintings (some loaned from the Royal Collection) in most of the rooms.
The house is opened on Sundays, by guided tour. The unseen north and east wings of the house (presumably containing former service rooms and bedrooms) have been converted into lettable premium office space. Outside, facing St James’ Park, is a private garden, not opened to the public.
Access to the house is via St James’s Place, off St James’s Street, or via an alleyway from Queen’s Walk. (You may get an external view of the south side of the house from Little St James’s St, but I did not go there)
Interior photography is not permitted except for two rooms, but there is a pictorial tour on the Spencerhouse website, and floor plans can be found online.