The prime minister wants to increase support during a tour of Britain this summer

Theresa May will go on a tour of Britain this summer in an attempt to convince sceptical Tory members to back her plan for Brexit.

The scale of unrest among grassroots Conservatives emerged yesterday as Boris Johnson used a resignation speech to galvanise the party’s membership against the prime minister’s Chequers plan.

Mrs May appears to have survived the most turbulent period of her leadership after defeating rebellions from the Remain and Brexiteer wings of her party.

Details have emerged, however, of a “tense” and “emotionally charged” meeting this week at No 10 between Tory association heads and Brandon Lewis, the party chairman. “A lot of people there were clearly upset,” the Conservative Home website reported.

Tory MPs pledged their loyalty to the