The leadership of British prime minister Theresa May is under serious threat after he most high-profile minister, Boris Johnson, quit as foreign secretary hours after her Brexit minister David Davis also resigned. May is coming under fire from her pro-Brexit lawmakers, such as Johnson and Davis, after she made them sign up to a Brexit policy which they believe would retain too-close ties with EU laws and regulations. Johnson was the flamboyant public face of the Vote Leave campaign, and his departure from May's government leaves her without the support of her party's most high-profile Brexit backers. There is intense speculation that May could face a vote of no confidence, sparking a leadership challenge. If 48 MPs write letters of no confidence to the chair of a powerful group called the 1922 Committee, Graham Brady, May will face the vote.