I'll work for Boris as sports adviser says Labour MP... to her party's fury

The announcement dealt a blow to Ken Livingstone's campaign by undermining his claim that Mr Johnson is an extremist who would put London's prosperity at risk.

Ms Hoey, MP for Vauxhall, told the Evening Standard: "Boris has talked to me recently about ways I could get involved if he should win, as he knows of my determination to make sport at all levels something Londoners can enjoy and be proud of.

"If Londoners choose Boris as Mayor this week, I would be glad to serve in that capacity."

Several Labour MPs called privately for Ms Hoey to be disciplined for what they saw as treachery two days before Londoners vote. Former defence minister Lord Moonie said: "I think she has overstepped the mark."

The Evening Standard has learned that Labour's Chief Whip Geoff Hoon was furious. He heard of the role only after it was announced by the Johnson campaign team and told Ms Hoey in a conversation later that she should have either refused it or kept it secret until after polling day.

Tensions were raised when Ms Hoey was spotted chatting to David Cameron in a passageway at Westminster last night, fuelling speculation she may defect to the Conservatives.

However, despite the fury of Labour colleagues, Ms Hoey escaped without any disciplinary action. The Prime Minister accepted her argument that her action was no different from the decision by Tory backbenchers Patrick Mercer and John Bercow to accept invitations from Mr Brown to act as advisers to the Labour government.

Labour MP Jeremy Corbyn said her action was "deplorable" and may have broken party rules.

Labour's rulebook say no MP can support an opposing candidate. Mr Corbyn said Mr Brown had made "a rather large mistake" by inviting Tories to work with Labour, muddying the rules.

In a statement that was approved by No 10, Ms Hoey dismissed speculation that she might defect to the Conservatives and denied her action amounted to an endorsement of Mr Johnson.

"This is not an endorsement of Boris Johnson for Mayor," she said. "I will be voting for my party and Labour candidates on Thursday.

"I am a Labour MP and I am standing for Labour at the next election. I support the Labour Government."

She criticised the Johnson team for the way it portrayed her decision. "The key part of the Boris Johnson statement - that I will be the first member of his administration - is wrong," she said.

"I have simply agreed to act in a similar position, for example to Conservative MPs John Bercow and Patrick Mercer, in that I have said that I will advise on a nonpartisan basis in respect of my lifetime commitment to bringing sport to the people of London." Mr Livingstone dismissed Ms Hoey as an "eccentric" and " semidetached" MP.

"But I'm surprised he's going to take her advice on sport because I think the reason Tony Blair sacked her at the end of his first term was because she'd been involved in all the fiasco over Wembley," he said.

Mr Johnson said Ms Hoeywould advise on issues such as protecting playing fields, boosting sports clubs and ensuring London's children benefit from the Olympics. He added: "I am determined to bring talent from across politics and the community to a new administration."

Ms Hoey was at the centre of speculation she might back Mr Johnson a week ago when she was scheduled to appear alongside him at a campaign event but pulled out, blaming ill health. Some MPs now believe she was going to announce her appointment then but lost her nerve.

Conservative leader David Cameron said he was "delighted" with Ms Hoey. But Liberal Democrat Brian Paddick said she was "bonkers".