Smart was a builders’ trade union activist and a leading figure in the Young Communist League (YCL) in the late 1950s.
He was a key speaker, along with engineers’ leader Claude Berridge, at the Whitsun Festival of Socialism held in
London in 1958, a reprise on the first successful attempt such an approach held in 1957. The Festival included Folk, Jazz, Choir, and the new Skiffle music. Alan Bush, Tom Russell and Ewan McColl were also present,
A pageant from Hyde Park to Trafalgar Square took place at which Willie Gallacher spoke and the Glasgow YCL choir sang.