Boris Johnson plunged Britain into constitutional uproar yesterday when he announced plans to shut down the UK parliament for five weeks, daring opponents of his Brexit strategy to vote down his government in a sharp escalation of tensions in Westminster.

The move was described by the House of Commons Speaker, John Bercow, as a “constitutional outrage”. Ruth Davidson, the popular pro-Europe Conservative leader in Scotland, is set to quit today, according to people briefed on her plans.

The prime minister asked the Queen to prorogue parliament between the second week of September and October 14 — the longest suspension since 1945. The monarch, who has so far avoided being dragged into the Brexit debate that has divided Britain since the 2016 referendum on EU membership, app-roved Mr Johnson’s request in a meeting of the Privy Council at her residence in the Scottish Highlands, Balmoral. The council advises her on political matters.