DAVID Cameron has avoided a humiliating Commons defeat on Europe thanks to Labour after he faced his first significant rebellion of the new Parliament by Tory Eurosceptics.

Some 27 Conservative rebels, supported by, among others, all 56 SNP MPs, six DUP MPs, four Labour MPs and Ukip's Douglas Carswell, voted for an amendment, tabled by arch-Eurosceptic Tory Sir Bill Cash, to the EU Referendum Bill to retain the so-called purdah rules, which seek to restrict Government activity in the 28-day run-in to elections and referendums.

The Prime Minister was helped in securing a healthy majority of 191 - the vote on the amendment was 288 to 97 - because Labour abstained, arguing there needed to be more clarity about the Government's intentions.

The vote followed an earlier u-turn by Mr Cameron, who, under pressure from all sides of the House, decided to introduce an amendment that meant the EU referendum could not take place on the same day as the Holyrood election and other polls next May.

Faced with another major rebellion on purdah, the PM dispatched Europe Minister David Lidington to write to Tory MPs to offer a concession that the Government would not spend public money to deliver mailshots to households in the last four weeks of the referendum campaign.

No 10 made clear that there could be even more concessions in the autumn to allay fears and reassure MPs that the Government was determined to ensure there would be a fair fight.

Steve Baker, one of the founders of Conservatives for Britain, which is poised to campaign for the UK to sever ties with Brussels, said there had been a "tremendous whipping operation" during the day with MPs being invited for talks with Foreign Secretary Philip Hammond "for reassurances".

Ministers have insisted the Government has no intention of being a major player in the referendum campaign, leaving it instead to the two official Yes and No campaigns as well as the political parties.

Yet, equally, it has warned that the normal purdah restrictions, which applied ahead of last September's Scottish independence referendum, would be "unworkable and inappropriate" because they would mean that important day-to-day business with the EU would grind to a halt.

Yet the reassurances were still not enough to persuade rebellious Tories against marching into the opposite lobby to support Sir Bill's amendment. These included former Cabinet Ministers Liam Fox, Owen Paterson and John Redwood.

Senior Conservative Bernard Jenkin insisted: "This is not about Europe; it is about how to conduct a fair referendum."

If the 25 rebels had been joined by all Opposition MPs, including Labour, then Mr Cameron's Government would have been defeated just nine weeks after the General Election given it has a working majority of just 16.

The vote will be a reminder to the Tory leader of just how fragile the Government's working majority is as he attempts to keep his party united on the deeply divisive issue of Europe while preparations continue for the in/out vote.

During the Commons debate, Sir Bill, who represents Stone near Stafford, made clear the Government's concessions had not allayed fears of an uneven playing field and stressed that there were "extremely sound reasons" for enforcing purdah before polls.

Pat McFadden, the Shadow Europe Minister, made clear Labour did not oppose the Government's wish to suspend purdah but called for "more clarity" over what it intended to do or publish during the referendum period.

Alex Salmond for the SNP ridiculed the Government argument that it could not function if purdah were imposed before the EU referendum, noting: "But that's what happens in each and every general election we have had. I didn't notice recently, in April and May, that the administration of this country ground to a halt; a lot of people thought it was better not having a fully activated government in the campaign period.

"If it can be done in each and every general election, then it can be done in this referendum campaign," insisted the MP for Gordon.