When Dave Nellist entered parliament in 1983 as the Labour MP for Coventry South East, he became one of Westminster’s best-known socialists. He was seen as a workers’ MP on a worker’s wage, donating more than half his salary to left-wing causes. But within a few years, he was embroiled in a bitter political dispute inside the Labour Party that ultimately led to his suspension and expulsion. He was associated with the Marxist newspaper Militan…