Prominent Labour MP Tom Watson has admitted to an "embarrassing mistake" tonight after voting the wrong way on changes to rules surrounding Fixed Odds Betting Terminals (FOBTs) - an issue he had personally led a campaign on.
In a blog post after the result, Mr Watson admitted this was the worst time to make such a mistake - but insisted it was "bound to happen" at some point in his Commons career.
He said: "I voted the wrong way as my head said put the cross in the 'no' box but my hand put the cross in the 'yes' box.
"On most days few would notice this act of tiny rebellion. Except this was the day in which I made the front page of the Daily Mail, leading the campaign against FOBTs.
Mr Watson was initially even more shocked after first thinking the vote had been lost by only one vote - joking he almost "jumped in the Thames".
The Labour MP Tom Watson, who quit as the party's election co-ordinator during the "media frenzy" over allegations surrounding the selection of the prospective parliamentary candidate for Falkirk, has tweeted:
Labour MP Tom Watson has questioned whether Home Office ministers were informed of the decision to arrest the partner of a Guardian journalist and called it "an embarrassment to the Government".
He told the BBC: "What I think we are going to see is this is sort of the intelligence services overstepping the mark - they are clearly trying to intimidate Glenn Greenwald - and that's an attack on journalism.
"I think politics needs to intervene to make sure it doesn't happen again."
An MP has called for police action after Rupert Murdoch was apparently recorded telling journalists he regretted the level of cooperation over phone-hacking and illegal payments.
Labour MP Tom Watson called for police to question Mr Murdoch over the alleged comments, telling Channel 4 News:
What I would like to know is what are they sitting on that they've not given the police. And I'm sure that this transcript and this audiotape should be in the hands of the police tomorrow because I hope that they're going to be interviewing Rupert Murdoch about what he did know about criminality in his organisation ...
Rupert Murdoch told Parliament one thing and told his staff another. He told Parliament that he was fully co-operating with the police, he told his staff that it was a mistake they were co-operating with the police.
Labour's election co-ordinator Tom Watson said his party enjoyed a good night in the local elections and South Shields by-election.
Speaking to the BBC Radio 4 programme, Mr Watson said "We had a good result on what we have seen so far, to get 50 per cent of the vote in South Shields, to win back the mayor in Tyneside, to make progress in the Westminster battleground seats within counties is good for us.
"In the Westminster battleground seats, places like Harlow, Hastings, Stevenage, Cannock, the Westminster seats we lost in 2010 and we need to win back in 2015, they are coming back to Labour in quite big numbers."
The MP for West Bromwich East said Labour leader Ed Miliband had been consistently told by voters that they felt a sense of "powerlessness" when it came to politics and its ability to change their lives.
"At the heart of this is economic failure, they feel the Government plan is not working and they feel the job of the Labour Party is to convince people there is a better way, that we can address this squeeze on living standards and give people more hope," he said.