The proscription of the SLL, together with the closed shop system of the time, made it impossible for him to find work in the mining or building trades, and he decided to adopt writing as a full-time profession.
His later play, The Talking Head (1969), recounts the experience of a talented writer driven to a nervous breakdown by the pressure of "episode delivery dates".
It was followed by The Lump (1967), the first fictional work directed by Jack Gold, who had begun his career on documentaries,[3] and broadcast as part of The Wednesday Play drama anthology series.
Both plays were based on his experiences in the building trade, and The Lump features an activist worker who frequently quotes Lenin and Jack London, establishing the political nature of Allen's work which was to continue throughout his career.
At the time, Allen said, "Without any undue humility, I'm saying this is the most lethal attack on Zionism ever written, because it touches at the heart of the greatest abiding myth of modern history, the Holocaust... privileged Jewish leaders collaborated in the extermination of their own kind in order to help bring about a Zionist state, Israel.
Lord Goodman wrote in the Evening Standard on 23 January 1987: "Mr Jim Allen's description of the Holocaust can claim a high place in the table of classic anti-Semitism.
With Loach as director, Allen wrote the screenplays for three feature-length films: Hidden Agenda (1990), which portrays the murder of an American civil rights activist in Belfast, Raining Stones (1993), a kitchen-sink tragicomedy set in Middleton, near Manchester, and, Allen's final dramatic work, Land and Freedom (1995), telling the story of an idealistic young Communist from Liverpool who joins the Government forces in the Spanish Civil War.