The PM could hang onto power until the autumn of 2021 under new plans being floated by a prominent minister Oli Scarff/AFP/Getty

Theresa May’s allies are plotting to keep her in Downing Street for at least another two years amid growing confidence that she will get her Brexit deal through parliament.

Her supporters in cabinet have been buoyed by what they believe to be a substantial shift in political arithmetic in the Commons. This follows secret talks between May’s chief Brexit negotiator Ollie Robbins and his European counterparts last week.

Plans being floated by a prominent cabinet minister would see May hang on to power until the autumn of 2021 when she would hand over the keys of No 10 to a new Conservative leader.

The new prime minister would then have about nine months to prepare their team before the next general election, due in May…