Thursday 28 March 2019 1:23 pm | Updated: Monday 03 June 2019 12:58 am

David Lidington warns Tory MPs a future Brexit deal must respect May’s withdrawal agreement

Theresa May's de facto deputy today cautioned that those who lead the next stage of the Brexit negotiations must abide by the current withdrawal agreement with the European Union.

In particular, David Lidington said, they must follow the rules laid out in the withdrawal agreement about “citizens rights, a financial settlement, and arrangements to secure an open border on the island of Ireland”.

Lidington's speech to the British Chambers of Commerce (BCC) conference today followed Prime Minister Theresa May promising to resign if MPs vote through her deal in a last-ditch appeal to get Brexit hardliners on board.

Her resignation opens the possibility of a Brexiter such as Dominic Raab or Boris Johnson becoming PM, and leading the UK towards a less close relationship with the EU.

However, Lidington warned that whether future negotiators want a Norway or Canada-style deal or even if the UK crashes out on World Trade Organisation (WTO) terms, they “must include as a starting point the withdrawal agreement that has been negotiated with the EU”.

He said any “future preferential or free trade agreement” with the EU would mean respecting the withdrawal agreement – the legally binding document that lays out the future relationship between the UK and the EU – on a financial settlement, citizens rights, and the Irish border.

In the past, notable leave-voting figures such as Johnson have said that the so-called divorce bill, which would see the UK pay around £35bn to £39bn, have expressed anger at having to pay Britain’s outstanding obligations to leave the bloc.

Johnson said in 2017 that the EU could “go whistle” over the figure.

Last night the former foreign secretary announced that he would be supporting May’s Brexit deal after she pledged to resign before the next stage of negotiations.

The PM's deputy threw his weight behind May's deal, saying he thought it is “the best choice available to us that respects the democratic verdict and safeguards the economic interests of this country", speaking “as somebody who campaigned very strongly for remain in 2016”.

He told the UK's business leaders assembled at the conference that it would mean “no disruption to your existing workforces” and said the alternative was “more division, more uncertainty, with all the risks that that will entail”.

The government is assessing its options to try and get the withdrawal agreement passed after speaker John Bercow blocked efforts to bring it back in front of the house in its current form for a third time.

Parliament will hold further “indicative votes” on Monday to try to work out which way forward has majority support in the House of Commons after it yesterday voted against all eight ideas brought before it.