By Baron Dunlop, former under secretary of state for Scotland

THE Prime Minister’s task is to deliver a deal that respects the referendum result and secures the support of both the EU and a majority ultimately in the Commons. It is multi-dimensional chess on steroids.

The agreement the Prime Minister was able to forge at Chequers was welcome. First, after many months it articulated a clear position, though whether it forms the basis of a deal with Brussels remains to be seen. Second, it recognises the reality of the UK parliamentary arithmetic following last year’s disappointing election result; there is no parliamentary majority for a so-called “hard” Brexit. Third, for the first time there is an agreed Cabinet position on the future relationship with the EU; collective responsibility among ministers can now – and should be – reasserted.

The resignations of David Davis and Boris Johnson do not change the fundamentals. They do not change the parliamentary arithmetic. They do not offer a viable alternative prospectus to the one presented by the Prime Minister. And neither do they make any more attractive to the mainstream of Conservative supporters inside and outside Parliament a Conservative leadership contest.

I can understand and respect the fact that Mr Davis felt he had no alternative but to resign. That is an inevitable consequence of being the Cabinet minister responsible for driving a policy, but not able to mobilise the necessary support or exert the influence in government to drive it in your preferred direction or speed. And the same can be said of Mr Johnson too.

In politics “constructive ambiguity” can aid progress and facilitate the final deal. But it is also the case that lack of clarity becomes an impediment to an agreement. There was always going to be a moment when the Prime Minister would have to choose on her preferred form of Brexit. Her choice was always going to disappoint one group of her supporters.

She must now demonstrate she can deliver the free trade partnership she has long promised and resist unreasonable attempts to further salami-slice the UK position. Becoming effectively a non-voting member of the EU, with all of the obligations of being in and few, if any, of the benefits of being out, would not be a happy outcome. And the EU member states need to consider if they have stretched the elastic as far as it will go – and to stretch it any further will reach breaking point. This is in no one’s interests.

Baron Dunlop is former under secretary of state for Scotland.