The veteran Labour politician Frank Dobson, who served as health secretary under Tony Blair, has died aged 79.
A popular figure in the party, he left government to contest the first-ever London mayoral election in 2000, coming third to ex-colleague Ken Livingstone.
Mr Blair said Mr Dobson had made an "immense contribution" to Labour's 1997 landslide election victory and was a politician of the "highest calibre".
Current Mayor Sadiq Khan said he was a "hero of the London Labour movement".
So sad to hear the news about Frank Dobson. A hero of the London Labour movement – his kindness, commitment to reducing inequality, and unique sense of humour will be much missed. Sending love to his family. https://t.co/Q93g0gRbVD— Sadiq Khan (@SadiqKhan) November 12, 2019
Labour leader Jeremy Corbyn said Mr Dobson had been passionate about reducing health inequalities as well as fine political company, remembering him as a "great raconteur, a great purveyor of stories and a great source of gossip around the House of Commons".
Mr Dobson served as MP for Holborn and St Pancras in central London for nearly 40 years before standing down in 2015, when he was succeeded by the shadow Brexit secretary Sir Keir Starmer.
Sir Keir said he would be remembered for his "straight talking, good humour and the passion he brought to every job he had", adding that "he dedicated his life to serve the people of Camden and the Labour Party he loved".
In a statement, Mr Dobson's family said he died on Monday after a long period of illness.
"His family would like to thank all the staff at the Homerton University Hospital for their outstanding expertise, commitment and care in the last few months and also the staff of York Hospital for his previous excellent care," they said.
"He also greatly appreciated the support of his many friends and former parliamentary colleagues."
Mr Dobson led Labour-controlled Camden Council during the 1970s before first being elected to Parliament in 1979.
He served in a number of shadow frontbench roles under Neil Kinnock, John Smith and Tony Blair during Labour's 18 years in opposition.
As Labour's first health secretary for nearly 20 years, Mr Dobson oversaw the abolition of the internal market in the NHS, but was frustrated at financial constraints initially imposed by the Blair government, which stuck to the Conservatives' spending plans for the first two years.
In 1999, he put himself forward as a candidate, many thought reluctantly, for the new post of London mayor.
However, his campaign was a troubled one and he was pushed into third place behind Mr Livingstone, who ran as an independent after losing the Labour nomination to Mr Dobson - and the Conservative candidate Steve Norris.
After his defeat, he never returned to government but continued in Parliament for a further 15 years.
Mr Blair said his late colleague was a politician of the "highest calibre" whose "often pugnacious style" never disguised his loyalty to the party and his commitment to "changing the lives of people for the better".
"He made an immense contribution to getting Labour back into power in the 1990s," he said in a statement.
"Despite the tight spending limits for the first two years, Frank made many important improvements to the NHS, an institution he cared about deeply."
In his own tribute, former chancellor and prime minister Gordon Brown said Mr Dobson had been a "highly successful and reforming" health secretary who "represented all that is good about Labour values".
"He was always popular with colleagues, never forgetting where he came from or the people he came into politics to represent".
And current Conservative Health Secretary Matt Hancock also praised Mr Dobson's "years of devotion" to the health service.
Just heard the news that Frank Dobson has passed away.— Matt Hancock (@MattHancock) November 12, 2019
From one health secretary to another, thank you for your years of service and devotion to our health service. pic.twitter.com/a5q24RMvQX
The traditionalist with a ripe sense of humour
By the BBC's parliamentary correspondent Mark D'Arcy
In another political era, Frank Dobson might have flown higher in a Labour government, but he entered Parliament just as his party began their long exile in the Thatcher-Major years, and by the time it returned to power, his face didn't quite fit any more.
As a classic product of Labour local government, he was a traditionalist on policy, and as Tony Blair attempted to shift "New Labour" towards a different approach, Mr Dobson was something of a holdout - a left-pragmatist rather than a starry-eyed Blairite.
His personal style was a holdout too - the Tory diarist Alan Clark found they shared a politically-incorrect sense of humour: "His [stories] are so filthy that really they're unusable, even at a rugger club dinner," he wrote in his diaries.
But Mr Dobson could quote Shakespeare with equal ease.
After Labour's 1997 landslide, he scrapped the previous Conservative government's internal market in the health service - only for his successor Alan Milburn to re-introduce a version of it.
By 2000 he was manoeuvred out of the Department of Health and into a thankless role as Labour's candidate for the newly-created London mayoralty. With the party machine behind him he won the nomination ahead of the left-winger, Ken Livingstone.
But when Livingstone ran anyway, as an independent, Dobson came a humiliating third in what was supposed to be a Labour city. He never returned to government.