Whether or not one agreed with the radical politics of the Labour MP Terry Fields, there was no denying that he was a man of principle. So much so, in fact, that Fields, a supporter of the Trotskyite Militant Tendency, went to prison for 60 days in 1991 rather than pay the poll tax. So angered was Neil Kinnock, then Labour Party leader, by Fields’s antics that he refused to accept a cheque for £427 from the Freedom Association to pay the poll tax bill and so release him from jail.

Fields declined to accept his full salary as an MP, honouring an election pledge to take only the equivalent of the pay that he had earned as a firefighter and to give the remainder to his constituency party, local causes in Liverpool and trade unions.

Fields, a class warrior to his fingertips, was for years a thorn in the side of Kinnock and a scourge of the Labour Party leadership in general.

“Nothing is too good for our class,” he said. “I will be a Militant if that means fighting for our class just like Thatcher is for hers.” He described Kinnock as “the biggest traitor since Ramsay MacDonald” when he criticised Militant at the Labour Party conference in 1985.

Terence Fields was born in Bootle in 1937, the son of a former dock worker, and was educated at Major Street County Secondary School and De La Salle Grammar School, Liverpool. In 1957 he became a fireman, later a fire prevention officer, in Merseyside County Fire Brigade and an executive member of the Fire Brigades Union, having been inspired to engage in politics by a Communist Party activist. In 1983 he was elected Labour MP for Liverpool, Broadgreen. It was a time when Militant Tendency dominated Liverpool City Council under the charismatic leadership of Derek Hatton, officially the council’s deputy leader but head in all but name.

In 1982 Fields was selected as Labour candidate for Liverpool Kirkdale, causing the chairman of the local Labour Party to resign in protest. His candidacy was endorsed by Tony Benn and then by Labour’s National Executive Committee. He failed to win the seat but was elected to the marginal Liverpool Broadgreen seat in June 1983. While campaigning, Fields drove around the streets of Liverpool with a red flag fluttering from his car.

Both Fields and his fellow Militant Tendency supporter Dave Nellist, who won Coventry South-East for Labour in the 1983 general election, urged Labour MPs to accept only a skilled worker’s wage of £130 a week. In his maiden speech Fields warned the Commons that the social upheaval to come would be worse than the 1926 General Strike, and said: “I wear my badge of Militant with honour.” He went on: “In time the whole working class will rise off its knees. You won’t be laughing then.” Sporting what became his trademark black leather jacket, Fields forecast the triumph of Marxism in Britain. He said that the proper name for privatisation was asset-stripping — a reward for those who had given millions to the Tories to help them to win the election.

In June 1983 he opposed a government ban on pigeon racing and in November that year he accused the Government of being complacent over drug abuse. In July 1984 he sponsored a motion attacking the murder of Chilean civilians by the secret police. In November that year he opposed cuts in benefits to the dependants of striking miners, and in January 1985, to Kinnock’s anger, he joined a protest over the miners that culminated in the suspension of the Commons. In April he called for a one-day strike by school students against youth training schemes. In November he voted against the Anglo-Irish Agreement. In May 1986 he led a march of schoolchildren through Cardiff in protest at social security cuts affecting students. In October he opposed a Bill to alter the time limit on abortions, saying he believed in allowing late abortions. In the June 1987 general election he almost doubled his majority. In April 1988 he urged non-payment of the poll tax, which eventually led to his own jailing for refusing to pay.

Fields and Nellist were suspended from the Labour Party in September 1991 for their links with Militant and banned from the party’s conference that autumn. But they continued as MPs in the Commons until December when Fields was finally expelled from the party for his Militant support.

In April 1992 he stood as an independent Labour candidate and came third behind the official Labour candidate, Jane Kennedy, who won the seat now known as Liverpool Wavertree.

Out of office, Fields became manager of a Liverpool pub called the Mayflower. When asked if he would continue in politics he replied: “I’ve never been in politics in the accepted sense. All I’ve been is the representative of ordinary people in my area.” Six months later the pub lease expired and he was out of work.

In retirement he played an active part in his social club in Bootle. In 2002 he rescued a woman from a burning house while on his way home from the club.

He is survived by his wife, Maureen, two sons and two daughters.

Terry Fields, MP and trade unionist, was born on March 8, 1937. He died of lung cancer on June 28, 2008, aged 71