The building is an unsurpassed urban design gem, with office space arranged in three blocks of varying height around two compact pedestrian courtyards.
In contrast, Smithson also designed the Robin Hood Gardens council housing scheme, completed in 1972 in London Docklands, which has been widely criticised as a system-built concrete monstrosity.
The scheme includes a total of 214 flats and maisonettes set in two elongated deck-access slab blocks that shield a large communal garden from hostile trunk roads on either side. However, tenants' complaints, mainly of water penetration and burglary, were 20 times higher than average.
Smithson was probably more influential through his teaching, particularly as resident guru at the Architectural Association in the 1950s and 1960s, than through the buildings he designed with his wife Alison. He also wrote prolifically, and last year published a double volume of his practice's complete works.
Smithson studied architecture at Durham before and after the Second World War and set up practice in 1950 with his wife, who died in 1993. Operating from their office in South Kensington, below the flat where they brought up their three children, they ran a model husband-wife equal partnership.