Veteran Labour MP Frank Dobson has confirmed that he will step down at the 2015 general election.
The former cabinet minister formally announced his decision not to seek a ninth straight general election win at a meeting of party members.
"I have decided to pack in when people are stopping me in the street to say they hope I am not going - rather than waiting until they ask why the hell I am still around," he said.
Now 74, the avuncular bearded Yorkshire-born politician has represented Holborn and St Pancras in London since 1979.
He was made health secretary by Tony Blair when Labour swept to power in 1997.
But his spell at the top table was cut short when the Prime Minister persuaded him to run as the party's candidate to be the capital's first elected mayor.
After finishing third behind former colleague Ken Livingstone and Tory Steve Norris, he returned to the backbenches and spoke out against a string of party policies including the Iraq War, top-up fees for students, the marketisation of parts of the NHS and longer detention without charge for terror suspects.
"It has been an honour to represent the people of Holborn and St Pancras for all these years and to have made at least some contribution to making it a better place to live," he said in a statement.
"I am proud of the people I represent. They get on together and help one another. Outsiders who have tried to stir up divisions have always failed. Common sense and human decency have prevailed.
"It has been hard work keeping up with the needs and aspirations of local people and helping resolve their problems. My constituents have been slow to chide and swift to bless.
"So I have enjoyed the job. I will keep at it until the next election and give whatever help I can to my successor."
Labour leader Ed Miliband said: "Frank is one of parliament's finest and he will be sorely missed.
"On behalf of the Labour Party I would like to thank him for his dedication, strong sense of social justice and his years of service to our party and our country.
"Throughout his 35 years in parliament he has fought for many causes, most notably our NHS, including his time as Labour's first health secretary for 18 years, but he has always put the people of Holborn and St Pancras first.
"I will miss his friendship, his wise words and his sense of humour.
"We wish Frank the very best."
A number of Labour MPs paid tribute to a politician David Lammy called a " great guy & tireless campaigner".
Shadow Northern Ireland secretary Ivan Lewis said: " Frank Dobson falls into category 'they don't make them like that anymore'.
"His contribution to constituency, party, country uniquely special."
With Mr Dobson having secured a majority of almost 10,000 in 2010, the seat will be very attractive to would-be MPs.
Among names tipped as possible successors alongside local politicians is former Director of Public Prosecutions Sir Keir Starmer.