Dolphin Square is a block of private apartments and business complex built near the River Thames at Pimlico in London, between 1935 and 1937. At one time, the huge development was home to more than 70 MPs, and at least 10 Lords. At the time of their construction the development was billed, according to Sir Nikolaus Pevsner as the "largest self-contained block of flats in Europe" and, to an extent, their design has been a model for later municipal developments.
A. P. Herbert, "Dolphin Square", 1935 (illustrations by H. M. Bateman) described the Square as 'a city of 1,250 flats, each enjoying at the same time most of the advantages of the separate house and the big communal dwelling place'; the provision of a restaurant made him fear that 'fortunate wives will not have enough to do. A little drudgery is good for wives, perhaps. The Dolphin lady may be spoiled'. This booklet was produced as a promotional puff for the firm that owned and built the complex, Richard Costain Ltd. On purchasing the site, Richard Rylandes Costain remarked to a colleague: ‘in two or three years we'll either drive up to this spot in a Rolls-Royce, or we'll be standing here selling matches’.
Sir Maxwell Joseph bought the complex in 1958 for £2.4 million, selling it to Lintang Investments. Westminster Council later owned the estate. It was sold to Westbrook Holdings (January 2006), and the hotel/restaurant closed down in 2006 only to have another hotel open in its place.
Accommodation is provided in 13 'houses' each named after a famous navigator or admiral. At the south (Thames) side of the Square the houses are Grenville, Drake, Raleigh and Hawkins. Moving from the river up the west side, there are Nelson, Howard, Beatty, and Duncan. An hotel and administration offices, situated at the north side of the Square, is in Dolphin House, previously known as Rodney. Heading south from the hotel there is Keyes, Hood, Collingwood and Frobisher.
The estate contains a swimming pool, bar, brasserie (all of which were renovated in 2008), gymnasium, and shopping arcade. In the basement are a launderette and car park. A tennis court and croquet lawn overlook the River Thames. Until 21 January 1970, London Transport bus route 134 showed PIMLICO Dolphin Square as a destination and actually terminated in Chichester Street.
The development has many judges, senior civil servants, and MPs living at favourable market rates. Notable residents have included: comedians Ben Lyon and Bud Flanagan; actor Peter Finch; politician Harold Wilson; writer Radclyffe Hall; former Lord Chief Justice Lord Goddard; Christine Keeler; journalist Norman Cliff; Anne, Princess Royal; politician William Hague. John Vassall, the Soviet spy, was arrested at his Dolphin Square apartment in 1962. It provided a base for the Free French during World War II and number 308 Hood House was used by MI5 section B5(b) responsible for infiltrating agents into potentially subversive groups from 1924 to 1946.
 In popular culture
British jazz baritone saxophonist Ronnie Ross released jazz album Cleopatra's Needle (1968), containing its first track titled "Dolphin Square", which according to the sleeve notes was "dedicated to a party, at which Zoot Sims was present, once held in a flat there ('It must have been a good one, because I don't remember it')".
- Norman Kipping (2004). "Costain, Sir Richard Rylandes (1902–1966), rev.". In H. C. G. Matthew and Brian Harrison. Oxford Dictionary of National Biography (Oxford: OUP, 2004). Retrieved 7 March 2007.
- Richard Davenport-Hines (2004). "Joseph, Sir Maxwell (1910–1982)". In H. C. G. Matthew and Brian Harrison. Oxford Dictionary of National Biography (Oxford: OUP, 2004). Retrieved 7 March 2007.
- Milmo, Cahal (30 June 2006). "Secrets revealed of gay 'honey trap' that made spy of Vassall". The Independent (Independent Print Limited).
- Masters, A. (1986). The Man Who Was M: The life of Maxwell Knight. London: Grafton Books. ISBN 978-0-586-06867-0.
- "Ronnie Ross - "Cleopatra's Needle". Discogs. Retrieved 11 January 2013.