Shadow Olympics minister Tessa Jowell is quitting frontline politics after two decades in Labour's top team, she announced today.
The Labour MP was instrumental in securing and delivering the London 2012 Games while in government and continued to play a key role in opposition.
Labour leader Ed Miliband said today the Olympics and Paralympics would not have been possible without Dame Tessa's determination.
Dame Tessa said it was a privilege to have been involved in the London games from start to finish and praised Olympians, Paralympians and the volunteers who helped the spectacular events to run smoothly.
She said: "It has been the greatest privilege to have served as part of Labour's frontbench team, in government and most recently in the shadow cabinet for nearly 20 years.
"To have been able to be part of planning and delivering the Olympic and Paralympic Games from start to finish is a rare opportunity in public life and that too has been a privilege. After 10 years with the Olympics and Paralympics, it is job done.
"I hope people across our country know that the Labour Party under Ed Miliband's leadership wants to speak for them, cares about them and is ready to serve them.
"Our country has changed this summer and for the better because of the power of the British people, the Games Makers and our great Olympic and Paralympic athletes."
Mr Miliband said Dame Tessa has left an "enormous" legacy and the country owes her a "debt of gratitude".
"Over her career, Tessa has been an amazing asset to the Labour Party and to Britain," he said.
"Her legacy is enormous. What we have seen at London 2012 would not have been possible without Tessa's determination and dedication, both in championing the bid and playing a major role in delivering the Games. For this, the whole country owes her a huge debt of gratitude.
"She served in several roles, both in government and opposition, with dedication. Her perseverance played a key role in improving the lives of millions of children by introducing affordable childcare and Sure Start.
"Tessa will be missed from the shadow cabinet, but I know from her dedication to public service that she has much more to contribute in the future."
The former social worker was elected to Parliament in 1992 and rose swiftly through the Labour ranks, becoming a close ally of former Prime Minister Tony Blair and one of the leading lights of the new generation of women ministers.
She was appointed public health minister after Labour's 1997 election triumph, was promoted to employment minister and minister for women in 1999 and joined the Cabinet as Culture Secretary in 2001.
It was in that role Dame Tessa, who represents Dulwich and West Norwood, refused to bow to civil service advice that Britain should not bid for the Olympics and also talked round a sceptical Cabinet.
Sports minister Hugh Robertson said: "I'd like to pay tribute to Tessa's excellent work on the Olympic and Paralympic Games.
"Not only did she play a vital role in the winning bid team but she laid the foundations for a successful Games, which was recognised in this year's Queen's Birthday Honours.
"I was pleased that, with the cross-party approach to the Games, Tessa continued to be involved throughout, with a position on the Olympic Board and as deputy mayor of the Athletes' Village during the Olympic Games. She took on both roles with her usual enthusiasm and expertise."