Westfield is one of 30 housing estates built across the UK between 1948 and 1984 by the development company Span, for whom Eric Lyons was the chief architect. Widely praised when built, and still much-loved today for their well-designed houses and intelligent and attractive landscaping, Span estates are a rare triumph of modern British mass housing. In his bookThe Spirit of Span Housing, James Strike writes that: "Span housing was the inspiration of two young men, who, during the 1930s, met as architectural students at the Regent Street Polytechnic. Eric Lyons and Geoffrey Townsend both had a keen interest in modern architecture […] They believed that there was a market for well-designed houses in carefully designed landscapes for the sort of people who recognised good design when they saw it – and they were right."

In an article published inThe Guardianin May 2007, the architecture critic Tom Dyckhoff wrote of Span houses: “From the 40s to 80s, architect Eric Lyons and developer Geoffrey Townsend built estates to 'span the gap' between jerry-built suburbia and architect-designed pads. Sharp, modern designs with space, light and well-planned interiors, plus lavishly landscaped communal gardens designed to foster a sense of community.”