What is the 'Malthouse compromise' and could it be Theresa May's best bet for Brexit deal?

Has the prime minister killed off her best shot at keeping the Conservative Party intact?

MPs behind a plan to unite Tories around a Brexit strategy don't think so, even though she seemed to tell business leaders in Belfast that she wasn't getting rid of the Irish backstop.

"The thing about the prime minister," said one of those MPs on Wednesday, "is she'll often stick with the same line until something else is on the table".

They are convinced that their so-called "Malthouse compromise" is still being taken seriously - "A lot of Government time and effort and brainpower is being exhausted on this," said another of its supporters.

The compromise was hammered out in the office of housing minister Kit Malthouse over nine days of secret talks between Tory backbenchers from the Leave and Remain wings of the party.

In short, it involves swapping the backstop for a series of technical fixes to keep the Irish border open, and if the EU won't accept that then continuing to pay the EU during a longer post Brexit "standstill period" while everyone tries to find a way forward or gets ready for no-deal.

Jacob Rees-Mogg of the European Research Group. Credit: PA

The MPs behind it - including senior members of the Euro-sceptic European Research Group (ERG) - think all this can command a majority of the Tory Party, which is at least one key hurdle cleared.

Mrs May's other backstop options of inserting an end date or an exit mechanism might win over some Conservative MPs.

But Tories on the ERG say it still creates too many barriers between Northern Ireland and the rest of the UK - even old fashioned customs stamps could be needed - and so "to accept it with a time limit, or some exit mechanism, is still a very difficult thing to do".

All of which could leave the Malthouse compromise as the prime minister's best bet in Westminster.

But agreeing a deal with Brussels is the other hurdle, and one that has no Irish backstop other than existing technical measures doesn't quite sound like their cup of tea.