Trade unionist and UCS work-in veteran;

Born: December 20, 1931; Died: May 7, 2012.

Sammy Barr, who has died aged 80 of cancer, was one of the architects of the historic work-in at Upper Clyde Shipbuilders in 1971. Affable, committed and, like his colleague Jimmy Reid, he was recognised as an inspiring speaker. Mr Barr, pictured, with Mr Reid, was among the union leaders famously photographed on the step of 10 Downing Street on the day they tried to convince Prime Minister Ted Heath to save the shipyards. Mr Heath refused and the chain of events that led to the work-in began.

Although there is still no settled view on who came up with the idea of the work-in, many say it was Mr Barr. Even if it was not, he was certainly one of the lynchpins who kept the protest going. It was Mr Reid who famously told the UCS workers that there would be no hooliganism, vandalism or bevvying, but it was Mr Barr, as the widely respected shop steward of the largest union the Boilermakers' Society, who made sure there wasn't.

Samuel Alexander Barr joined the shipbuilding industry straight from school when he was 15 years old. He became an apprentice welder with Charles Connell and Company in Scotstoun and quite quickly became involved in trade union activism. He became shop steward for his fellow apprentices before taking up the same role for the welders in the Boilermakers' Society.

By the time of the crisis at UCS, in the early 1970s, Mr Barr had become a leading figure in one of the biggest unions on the shipyards. When the Government refused to bail the company out, he became a key member of the co-ordinating committee that masterminded the work-in. It was a close-knit team that included workers from all levels of the business, including management, and it confirmed Mr Barr's life-long friendships with fellow UCS activists such as Jimmy Airlie and Sammy Gilmore.

Speaking on the 40th anniversary of the beginning of the work-in last year, Mr Barr said there had been a marvellous atmosphere among the 8500 workers. Even so, it was a ground-breaking idea and needed discipline to make it work and it was the likes of Mr Barr who provided it.

Mr Barr's former colleagues agree that he was affable and easy to talk to but also agree that he had considerable political commitment, not only to the right to work and protection for the rights of young working people but also to the belief that the shipbuilding industry should be protected.

In the early 1970s he stood as a parliamentary candidate for the Communists and some believe it was this, and widespread anti-Communist feeling, that prevented him rising to become a leader of the Boilermakers' Society.

After his retirement – he remained in shipbuilding his working life – Mr Barr carried on his trade union work. He was president of the retired members' association for the GMB and a branch secretary in Glasgow right up until his death. His campaigning zeal also extended to local issues in Partick where he lived; his grandson Lee Carson said his grandfather had campaigned to prevent the closure of a park in the area.

After moving on from the Communist Party, Mr Barr became a Labour Party member, although he was very much of the Old Labour school. He knew Tony Benn well and last year, at an event to mark the work-in's anniversary, Mr Benn presented Mr Barr with a medal to recognise his contribution.

There is still some debate, 40 years after the work-in, about whether it was successful long-term. Certainly, the Government backed down at the time and many argue that shipbuilding only exists on the Clyde today, albeit in a reduced form, because of what Mr Barr and his comrades did. Mr Barr is survived by his wife Janet and four children.