Cllr Nick Stanton has announced his resignation as leader of the Southwark Liberal Democrats after his party's defeat in last week's local elections.
Cllr Nick Stanton, who represents Riverside ward in Bermondsey, has been Lib Dem leader since 2000. He has led Southwark Council since 2002, first as the head of a minority administration and more recently in coalition with the Conservatives.
At last week's local elections Labour won a clear majority of seats on the council, returning Labour to power after eight years in opposition.
The Lib Dems lost two seats to Labour in Newington ward, one seat in East Walworth and another in Chaucer ward, with Labour also picking up seats from the Greens and Conservatives in the south of the borough.
"School results are now the best ever, our streets are among the cleanest in London, and our community councils are a great example of empowerment and engagement. We've made great strides in making Southwark a greener place, with action to reduce carbon emissions and an eightfold increase in recycling with much more to come.
"I believe it is vital that the regeneration of the Elephant & Castle and Aylesbury Estate are completed in order to end the cycle of poverty which has blighted too many families for too long.
"I am a strong believer in local democracy and must roll with the punches. And I will do all I can to make sure that the hand over to the new administration is as smooth as possible.
"It has been a huge privilege to serve the people of Southwark as leader of the council over the last eight years. I have given it everything I have to offer and have hugely enjoyed the role.
"However, I have only been able to work as hard as I have thanks to my wonderfully supportive and uncomplaining wife and children. I have decided to stand down as leader of the Liberal Democrat group – after 10 years – so that I can, in the time-honoured phrase, spend more time with my family.
"I shall continue to be an active councillor for Riverside ward and support my colleagues as fully as they have supported me."
The Liberal Democrat group will elect a new leader on Monday 17 May.
Southwark Council now has 35 Labour councillors, 25 Lib Dem members and three Conservatives. The first meeting of the new council will be held on Wednesday 19 May.