Brenda Dean, Lady Dean of Thornton-le-Fylde, who has died aged 74, became one of the best-known trade union leaders in Britain as a result of her leadership of Sogat during the Wapping dispute in 1986-87, a brutal confrontation with Rupert Murdoch’s News International that would prove a watershed for the future of the print industry. She was a forward-looking pragmatist whose attempts to resolve the strike enhanced her status within the wider trade union movement but undoubtedly at the eventual cost of her own long-term career within it.

She was bitterly denounced by some people in the militant Fleet Street chapels (union branches) as a “Judas”, she was derided as “a film star” because of her blond good looks and her leadership was decried when she put the survival of the union, with 90% of its members in the provinces, ahead of what was essentially a London dispute.

Moves resumed later to merge Sogat (the Society of Graphical and Allied Trades) with the much smaller National Graphical Association and in 1991 Dean was narrowly defeated for the post of general secretary of the new Graphical, Paper and Media Union, which is now part of Unite.

In 1992 she resigned from her No 2 post in the GPMU after what she described as the only unhappy year of her working life. She was appointed to the House of Lords, which she described as having “some aspects of a dinosaur park”, on the recommendation of the then Labour leader, John Smith, the following year. She joined the privy council in 1998.

Dean had demonstrated her recognition that change was under way in the print industry early in her 33 years as a full-time trade union official. She had joined the Manchester branch office of the National Union of Printing, Book-binding and Paper Workers as a 16-year-old administrative assistant after a short spell in a Lancashire print firm that she had found tedious and uninteresting.

She progressed gradually through the union but within 10 years became a delegate to her first national conference, proposing a motion on education. She learned her speech by heart and deliberately chose to wear an orange wool A-line coat dress to ensure that she stood out even more among the suits of the largely male membership.

In 1972, when appointed as assistant secretary of what was by then the Manchester branch of Sogat, she succeeded in reversing the branch’s opposition to the advent of new technology in printing. It was a signal of what would lie ahead, both for her and the traditions of the industry. Four years later, she was secretary of the branch and in 1983 she was elected as national president, second in command of the union.

When she took over as general secretary in 1985, defeating six other candidates and polling almost double the support of the leftwing candidate who was her nearest challenger, she became the first woman elected to lead a major industrial union. At the time, women made up 40% of the membership of trades unions, but only 3% of full-time officials were women.

One of her first missions was to lead a 10-person delegation of her officials to the US and Canada to look at the impact of printing developments there. “Like it or not, the era of ‘new technology’ in Britain’s newspaper industry has arrived,” she wrote in a tough introduction to the report of their findings. “We are fast approaching now the eye of the storm …”

She had already met Murdoch, amid cloak-and-dagger privacy in a London hotel room, when she was first elected. He was clearly anxious to discover if she could deliver reform and help end the wildcat strikes among her London members that were causing endless stoppages in Fleet Street production.

She told him: “I don’t know – it’s a mess” and that she needed a few months to assess it. His response was to tell a colleague that he did not believe she had the “bottle”. He advanced his plans to move production to Wapping, which led to the conflict the following year.

During the dispute, Dean flew secretly in Murdoch’s private jet to meet him in California to try to negotiate an end to the strike. He barbecued lamb chops for them both alongside his pool in Beverly Hills as they discussed the way forward. “All he wanted to do was produce newspapers,” she later wrote sympathetically, attracting inevitable criticism from her union militants.

On another occasion, when the strike was collapsing, she flew via Concorde – travelling incognito from Paris – to meet a Murdoch official in a New York airport hotel to seek compensation for her 5,000 sacked members. “We were beaten,” she would write in her memoirs. “That was the harsh truth of the matter.”

Brenda was the elder of two children of Hugh and Lillian Dean, who were both from Salford families. Her father was a railway signalman and her mother worked in a carpet factory. Brenda was born during a second world war air raid. The family moved to Eccles, where she and her brother, Bobby, were brought up in a house with no bathroom and an outside lavatory. It was a happy, stable childhood: she attended St Andrew’s Church of England primary school and completed her formal education at Stretford high school for girls, where the pupils were taught commercial skills for office work. She played the tambourine and sang Jesus Wants Me for a Sunbeam with the local Salvation Army choir.

As a member of the Lords, Dean took on a huge range of public appointments and as a non-executive company director. Her responsibilities included chairing the armed forces pay review body (1999-2004), the Covent Garden market authority (2005–13) and the Housing Corporation, now Homes England, (1997-2003). She was a member of the national committee of inquiry into higher education (1996–97) and the royal commission on House of Lords reform in 1999, and was a member of the Labour opposition frontbench in the Lords from 1994 until 1997.

In 1976, she met Keith McDowall, a former journalist who was then a government press officer, and they became partners the following year. He later became deputy director general of the Confederation of British Industry and they married in 1988. He survives her.

• Brenda Dean, Lady Dean of Thornton-le-Fylde, trade unionist, born 29 April 1943; died 13 March 2018