Lib Dem fightback t-shirt
The Liberal Democrats may have to re-run their election to select the party's candidate for Mayor of London Getty

The Liberal Democrat fightback in London could take an extraordinary turn as the only candidate to become the party's Mayor of London hopeful could lose the selection election. Caroline Pidgeon, the leader of the Liberal Democrats at City Hall, was shortlisted alongside former councillor Duwayne Brooks.

But Brooks, a friend of Stephen Lawrence who was with the teenager when he died in 1993, had to pull out of the election as he is set to review Northamptonshire Police's stop and search powers. The move meant that Pidgeon, 42, become the sole candidate in the leadership contest.

However, despite having a clear run to victory, Pidgeon could still lose the election as Liberal Democrat members have the option of choosing "none of the above" on their ballot papers. A Liberal Democrat source told IBTimes UK that the outcome would be "very, very unlikely", but a majority for "none of the above" would trigger a re-run of the whole selection process.

"Unfortunately, Duwayne Brooks has since withdrawn from the mayoral selection owing to a new professional commitment with a police authority, which prevents him from going forward," a party statement released in August said.

"We are therefore proceeding with a shortlist of one candidate plus the standard option to vote tp re-open nominations. Eligible London members will be asked to vote for their first preference for London mayoral candidate shortly."

The results of the election are expected to be announced in the same week as the Liberal Democrat conference in Brighton on 19 September, where the party will hope to bounce back after a dreadful election performance that left the yellows with just eight MPs.

New leader Tim Farron vowed to "fight back" after beating former care minister Norman Lamb in the party's leadership contest in July.

"Pick a ward, any ward, and win it next May. Winning elections isn't rocket science but it is a science – do it, enjoy the fight, enjoy stunning the opposition as the comeback kids prove them wrong and we are uplifted by the difference you can make when you win," he said during his first speech as party leader.

"We may not be able to change Britain from the top down just for the moment, but we can change lives from the bottom up – that's community politics."

The Westmorland and Lonsdale MP has two political challenges next year in the shape of 2016 local elections and the ongoing debate around the EU referendum, which could be held in the same year.