By 1975, Robinson was the union convener of the Longbridge plant in Birmingham, having worked his way up from the shop floor to serve as the deputy of the previous convenor, Dick Etheridge, a fellow member of the Communist Party.

An article by Frank Hughes in Workers' Liberty suggests that Robinson, by supporting the introduction of the "measured day work" system in place of piecework and by encouraging the adoption of "participation", in fact destroyed the relationship between stewards and the shop floor and left them unable to control unofficial strikes.

[11] A 2002 BBC documentary series by Peter Taylor revealed that in the late 1970s MI5 had been attempting to undermine Robinson through an agent they had placed amongst his union officials; Edwardes stated that he had been "privileged to read minutes of meetings of the [...] joint committee of the Communist Party and our shop stewards", which had been passed to him via the Government.

[12] Taylor's documentary suggested that this was a result of the MI5 agent's activity, with Edwardes acknowledging that the removal of Robinson was in some ways necessary for the company's preparations to bring the new Austin Metro into production.

Longbridge was being substantially redeveloped and expanded for the new car, whose assembly was heavily automated in comparison to previous models and job losses would have been inevitable: "It was planned only in the sense...well, the answer is 'Yes', from a strategic point of view we knew that we couldn’t have the Metro and him.

[4] He became a sales representative for the Morning Star newspaper,[4] worked as a tutor in trade union studies during the 1980s and 1990s, and was national chair of the Communist Party of Britain for a period in the 1990s.