Campbell's section of the GLC department of architecture pioneered radical forms of public-sector housing, often employing some of the brightest architects. The department employed more than 250 staff at its peak.
High-density GLC estates, such as the Canada estate in Bermondsey, south London, were designed by Campbell's branch with bold combinations of high- and low-rise blocks. After the collapse of Ronan Point in east London in 1968 the branch turned its attention to low-rise high-density forms. It also experimented in industrialised building, including a three-storey block in Stoke Newington built using metal containers.
Unfailingly affable and approachable, Campbell was a natural committee man. He served on the RIBA council for 22 years, as vice-president for two years.
Like several senior architects at London council he was also a member of the then Communist Party of Great Britain and turned down a CBE.