London mayor Boris Johnson to stand for Parliament

The announcement ends months of speculation. Picture: Getty

“I have not got any particular seat lined-up but I do think... in all probability I will try to find somewhere to stand in 2015,” he said during a question-and-answer session following a speech in London.

He added: “It’s highly likely I will be unsuccessful in that venture.”

Mr Johnson said that he intended to serve out his full term as mayor which runs to 2016.

Mr Johnson said people should “never underestimate the possibility of this going badly wrong - I will try”.

Asked if his target seat would be within the M25 or in a constituency in the north of England, he said: “This is a matter for the (local Conservative) association. I am not going to presume to talk about which seat I might go for.”

Mr Johnson’s declaration that he intends to find a seat finally puts an end to months of speculation about his ambitions to make a return to Parliament.

It immediately raised the prospect that he could emerge as a challenger to David Cameron if the Conservatives are defeated or again fail to secure an overall Commons majority.

His announcement came at the end of a speech in which he raised the prospect that Britain could leave the European Union if Mr Cameron fails to achieve his promised reforms.