Ruth Davidson backed the statistics watchdog that rebuked Boris Johnson for repeating claims that Brexit could allow an extra £350 million a week to be spent on public services Robert Perry for The Times

Ruth Davidson has called for “serious people” to take charge of Brexit in a renewal of her attacks on Boris Johnson on the eve of the Conservative Party conference.

Ms Davidson, tipped as a future leader of the party, says in an interview with The Times today that “overoptimism” about the future of Britain outside the EU “sells people short”.

Her intervention means that the Tory conference in Manchester will begin tomorrow with two of the party’s most popular and charismatic figures at odds.

Theresa May waits at the EU Digital Summit in Tallinn. Ms Davidson backed the prime minister to lead the Tories into the next general election VIRGINIA MAYO/AP

Mr Johnson issued a direct challenge to Theresa May last night by making four Brexit demands and telling her to increase pay faster. In his second challenge in as many weeks, the foreign secretary told The Sun that she must lift…