Three local Tory MPs are set to defy David Cameron tomorrow by demanding a quickfire Bill to guarantee a referendum on quitting the European Union.

Philip Davies (Shipley), Stuart Andrew (Pudsey) and Craig Whittaker (Calder Valley) are among up to 100 Conservatives piling pressure on the Prime Minister.

The trio will back an unprecedented amendment to last week’s Queen’s Speech that expresses “regret that an EU referendum Bill was not included” which would mean MPs from the governing party voting against their own legislative programme.

To try to calm dissent, Downing Street has allowed backbenchers, and unpaid ministerial aides, a free vote – which means they will not, technically, be rebelling.

And Mr Cameron rushed out a pledge to publish his own draft Bill in an attempt to persuade his MPs to back down – a strategy that appeared to have failed last night.

Mr Davies said he accepted an in-out poll could not be staged before 2015, because of Liberal Democrat opposition within the Coalition.

And he had “total trust” in the prime minister’s pledge to stage a referendum before the end of 2017 – after renegotiating different membership turns.

But he said: “Because of the broken promises, by a number of politicians, on an EU referendum in the past, it is vital that he takes all the steps he can – in this Parliament – to prove beyond doubt to the public that this will happen.

“That is why I will be supporting the amendment.”

That message was echoed by Mr Andrew, unpaid aide to Cabinet Office minister Francis Maude, who said on Monday: “My intention is to support the amendment.”

But fellow Conservative Kris Hopkins (Keighley) said he was likely to abstain, arguing Mr Cameron had already provided “assurance to people that the referendum will be delivered”.

He said: “We must not forget that, before the referendum takes place, the prime minister will seek to renegotiate and recast this country’s relationship with Europe.

“It is vitally important that a proper national debate takes place between now and then.”