Kevin McNamara, long-serving Hull MP

He had been elected, with a 5,351 majority, in the January 1966 by-election that followed the death of Henry Solomons. It was a victory attributed by some to the promise by the transport minister, Barbara Castle, during the campaign, that the Humber could have the bridge it had long wanted.

Labour denied it had been a bribe, but Mr McNamara nevertheless was returned with a fivefold increase on Mr Solomons’ majority in what had, before his brief tenure, been a Conservative stronghold.

The new MP, the son of a seaman, soon won the trust of his new constituents.

He had been born on the other side of the country, into a Roman Catholic family in Crosby, Merseyside, and came to Hull first to take a law degree.

He met and married his wife, Nora Jones, and took a job as head of history at what was then St Mary’s Grammar School in Hull, before becoming a law lecturer.

He first tried to enter parliament in Bridlington, in 1964, but the town was a Conservative fortress.

Once at Westminster, he became parliamentary private secretary to the economics minister, Peter Shore. But his position on the party’s left, and his membership of the Tribune group, did not chime with the views of the prime minister, Harold Wilson, and he never held a ministerial office of his own.

However, in opposition, he was on the front bench as spokesman on defence from 1982 to 1987 and on Northern Ireland, under Neil Kinnock, from 1987 to 1994.

In that capacity, he was an advocate for the Catholic church in Ulster, and held a deeply-felt attachment to the ideal of reunification.

He was a popular figure in Dublin, where the former prime minister, Garret FitzGerald, said that Mr McNamara’s former boss, James Callaghan, “seemed to regard Kevin as an Irish politician” rather than a Labour spokesman.

It was the election of Tony Blair to the Labour leadership that ended his time in the front ranks. He was the first to admit that did not conform to the image New Labour was cultivating. “That’s because I’m fat and bald and green,” he said.

He was replaced by Mo Mowlam and demoted to be spokesman for the civil service but resigned after a year, telling Blair that a democratic socialist should not be “an ambulance man to capitalism”.

Blair, for his part, described Mr McNamara as “a really lovely man but wedded to the old policy.”

But he remained in the Commons for another decade, and by the time of his retirement he had fought 11 elections. His time was characterised by his staunch support for the trade union movement and by his promotion of private members’ bills on animal rights and the law that prevents Catholics from becoming monarch.

He retired to Merseyside, and 10 years ago completed a PhD in Irish studies at Liverpool University.

He is survived by Nora, sons, Julian, Edwin and Brendan, and daughter, Brigid. Another son, Kieran, died in 2013.