Rebel Euro MP Steve Baker was among 37 Conservatives to rebel against the government last night on a vote over the upcoming EU referendum.

Mr Baker, a leading voice over Britain’s involvement in the EU, joined fellow south Bucks MP and former cabinet minister Cheryl Gillan in rejecting proposals for ‘purdah’ rules in the run up to the national vote.

The Wycombe MP warned in parliament that many people were concerned about “tipping the scales using taxpayers’ funds” if the government was allowed to spend money campaigning on either side of the vote.

And he sided with Labour, the Scottish National Party and sections of his own party to reject the changes to current rules governing the use of civil service efforts during the 28-day period.

Speaking on the debate, he said: “It might be helpful to return to the origin of this problem: some people, including many Conservative Members, are concerned about tipping the scales using taxpayers’ funds.

“If this place is for anything, it is about Members choosing to restrain power through the law, and that is what we are seeking to do.

“Ministers might be tempted to take steps at the last moment to help influence the result, so we want to ensure that they are appropriately restrained in the usual way through normal purdah rules, or as close to them as we can get.”

Mr Baker, who founded the eurosceptic group Conservatives for Britain earlier this year, added: “I do not accept that the Government should redefine the scope of purdah.

“I want to be able to say at the end of the referendum that it was free and fair. If I find myself on the wrong side, I would like to be able to say that I accepted the result, and then take appropriate steps.

“I do not want to be left in a position where I am able legitimately to complain about the referendum’s fairness.”

Mr Baker said that to allow the changes to the rules introduced in 2000 would leave too much “wiggle room”, and that the plans should be “shut down”.

The rebellion marks the first defeat for the new Conservative majority government since it took power in May.

It comes despite ministers watering down the proposals before the vote, which Labour called “humiliating” for Prime Minister David Cameron.

And another Bucks MP, Europe Minister David Lidington, said the government’s concessions were an offer of “bridge building” – but one that one was ultimately rejected by parliament.