Senior figures from Old and New Labour have paid tribute to former Cabinet minister and party stalwart Barbara Castle, who died yesterday aged 91.

Baroness Castle of Blackburn, described as the most formidable woman politician of the 20th century after Margaret Thatcher, grew up in Bradford and kept links with the city throughout her political career.

Her main legacy to British politics was the breathalyser, which she introduced as transport minister, and is probably the biggest life-saver of all on Britain's roads.

Baroness Castle, the left-wing flame-headed political tornado, was the best-known woman parliamentarian of her day and once looked like becoming Britain's first female Prime Minister.

Born in Chesterfield, she lived her formative years in Bradford, moving to the city as a child to live in Toller Lane with her family.

She was a star pupil at Bradford Girls Grammar School and even after she entered the Commons as Labour MP for Blackburn in 1945 aged just 32, she never forgot her Northern roots.

Her political interests were established early on, winning 17 seats for Labour during a mock election at the school before going on to become a member of St Pancras Borough in 1937, and entering the commons as a Labour MP for Blackburn in 1945.

Baroness Castle kept her links with the city throughout her career, and was awarded the city's highest honour - freedom of the city - in 1997. She is pictured receiving the award. Artist David Hockney is now the only other Freeman of the City.

Speaking at the time she explained how living in Bradford had influenced her life.

"It was an experience at the start of my most formative years," she said.

"It was good political training in an industrial area - a stimulating experience. City Hall was the building which impressed me most; it symbolised civic pride."

Baroness Castle was a champion of Yorkshire causes throughout her life, and to the end was active in promoting Bradford's Capital of Culture Bid.

Right up to her death, she remained one of the toughest, and most unbending politicians in the business.

She was a tiny figure but on the rostrum, right into her 90s, she could hold a Labour Party conference spellbound and the Labour Party leadership in thrall - and some trepidation - as she tub-thumped her way through speeches with as much verve and fire as she produced in her youth.

Baroness Castle's political career spanned the bulk of the 20th century and she was outspoken on what she regarded as the ills and injustices of the society she served.

Bradford North MP, Terry Rooney, who knew her for about 30 years, said she was a passionate, committed politician.

"She was small in stature but a political giant," he said. "She was so intelligent and sharp and very witty. But I doubt she had an enemy in the world because everybody loved her."

"She will leave two major legacies. One is the breathalyser which cut road deaths by a thousand a year. The other is SERPS - hundreds of thousands of retired people have an extra £78-a-week because of what she did."

Bradford South MP Gerry Sutcliffe praised the women who helped launched his political career back in 1994.

He said: "She was a fiery politician with deep convictions. She stood for what she believed in and said so. She was very rooted in the Labour Party

"She was a central player in the Labour Party over the last century and will be very sorely missed."

The New Labour Government which Lady Castle rounded on for failing to bring back the link between pensions and earnings she had introduced, last night paid tribute to her life.

Tony Blair described her as a heroine, while Foreign Secretary Jack Straw said Lady Castle was his "teacher, mentor, friend and critic".