EU referendum: Chris Grayling asked David Cameron for assurance he would not be sacked after Europe vote

Mr Grayling was understood to be on the point of resigning two weeks ago to take on a leading role in the Out campaign

Chris Grayling agreed in return not to campaign for a leave vote until after the renegotiation (Reuters)

The Eurosceptic cabinet minister Chris Grayling sought reassurance from David Cameron that he would not be sacked in a “revenge reshuffle” after the EU referendum.

Mr Grayling was understood to be on the point of resigning from the Government two weeks ago to take on a leading role in the Out campaign. But he was persuaded to stay on after he received assurances from Mr Cameron that he could campaign for a “leave” vote and continue in his job as Leader of the House Commons after the referendum.

In return Mr Grayling agreed not to damage the Government by resigning early and promised not to declare for a “leave” vote until after negotiations were completed.

Downing Street sources have denied that Mr Grayling had threatened to resign. However they pointed out that Mr Cameron had privately told other cabinet ministers that they would be free to campaign for the “leave” campaign before Christmas .

The deal underlines the efforts by Downing Street to control the splits in the Conservative Party over Europe in the run-up to the referendum. It has emerged that Downing Street had recruited the former Tory minister Nick Herbert to lead the Tory campaign to stay in the EU.

With the latest polls showing a six-point lead for the “leave” campaign Mr Cameron wants to ensure that the vast majority of his cabinet colleagues support his position – while those who oppose him do so in the knowledge that they will only be able to return to government if they avoid making the campaign too divisive.

On 17 January it was reported that the Justice Secretary Michael Gove had agreed not to support the “leave” campaign while Downing Street is also attempting to woo the London Mayor Boris Johnson. Mr Cameron is understood to have agreed to Mr Johnson’s suggestion to change domestic law to make clear that Parliament is sovereign and can override European law.

Downing Street is confident the most of the pieces are in place for a successful EU renegotiation deal to be agreed at next month’s European summit. The Sunday Times suggested Mr Cameron has won the agreement of other leaders for the so-called “emergency break” – enabling the Government to block new EU jobseekers from coming to the UK if public services become overwhelmed.

The Government is also working with France and Germany on a compromise agreement that would allow Mr Cameron to claim that he has cracked down on migrant benefits. Speaking on 17 January, the former Chancellor Lord Lawson dismissed the renegotiation as “inconsequential”.