Gardiner was born and raised in Chelsea in London. He was the younger son of Clive Gardiner, painter and principal of Goldsmiths College from 1929 to 1958, and Lilian Lancaster, also a painter and one of Walter Sickert"s favourite pupils at the Slade.
He was educated at Dulwich College, and served in the Royal Navy from 1942. He studied at the Architectural Association and qualified as an architect in 1948.
He then worked for Wells Coates, then for short periods with Richard Blow and Peter Dickinson, and with Maxwell Fry and Jane Drew. He worked with Richard Sheppard from 1951 to 1957, working mainly on schools. The original building was demolished, but the Tuscan portico was left standing as an architectural feature in front of the house.
He also worked on many school buildings in and around London.
He received the Officer of the Most Excellent Order of the British Empire in 2002 for his contribution to community architecture. Concerned at the precarious nature of his profession, and the number of projects that were never built, he also taught architecture.
He taught at the Architectural Association from 1955 to 1956, and at the Oxford School of Architecture (now part of Oxford Brookes University) from 1957 to 1968, at the University of Westminster from 1970 to 1974, at Washington University in Street Louis in 1978, at Cheltenham College from 1979 to 1981, and at the University of London from 1981 to 1986. Gardiner was also a writer
He wrote a thriller, Death of an Artist in 1958.
He wrote for the London Magazine for 37 years, from 1964 to 2001, and was architectural correspondent for The Observer for 23 years, writing a weekly column from 1970 to 1993. He also wrote for The Spectator, The Times, the Architectural Review, and the Royal Institute of British Architects Journal. He also wrote several books on architectural subjects, including Evolution of the House (1974), a monongraph on Le Corbusier (Fontana Modern Masters, 1974), Kuwait: The Making of a City (1984) and The House: Its Origins and Evolution (2002).
He wrote two biographies, Epstein: Artist Against the Establishment (1992), and Frink, a life of the sculptor Elisabeth Frink (1997).
Le Corbusier was a significant influence on his professional work, and he knew both Jacob Epstein and Elisabeth Frink. He also published poetry, and exhibited paintings and drawings.
He died at Pembury in Kent.
