London: Theresa May devoted most of her first hours as Britain's Prime Minister on Wednesday to naming the key members of the team that will have the task of implementing voters' decision to leave the European Union. She appointed Former Mayor of London Boris Johnson as the country's new Foreign Secretary. Until now a back-bencher, the promotion will cascade Johnson onto the world stage. Johnson served as Mayor of London from 2008 until this year when he was replaced by Sadiq Khan. He was elected last year as MP for Uxbridge and South Ruislip, but had served previously as an MP from 2001, resigning in 2008 when he became Mayor of London. He has taken over the job from Philip Hammond who has replaced George Osborne as Chancellor of the Exchequer, Xinhua reported. May has also created a new cabinet job, Secretary of State for Brexit, likely to be called the Brexit Secretary, tasked with steering Britain out of Europe following last month's referendum vote. The job has been handed to David Davis who has previously served as a Europe Minister. Current Defense Secretary Michael Fallon has kept his job. After Cameron resigned as prime minister following the Remain camp's defeat in the EU referendum, Johnson had been tipped as a favourite to replace him at 10 Downing Street. But on the day nominations closed Johnson caused a shock by announcing he had decided not to stand in the leadership contest. Hammond was the first cabinet member to be announced by May, naming him as her next door neighbour at 11 Downing Street. Hammond had served as foreign secretary in Cameron's cabinet, but he has had previous experience of a Treasury role. George Osborne, Chancellor of the Exchequer in David Cameron's cabinet has resigned from the government, in what was the first shock as new Prime Minister Theresa May started the task of appointing her own front bench team. For Hammond the job means a return to the Conservative's Treasury team where he previously served as Shadow Chief Secretary to the Treasury. In 2007 he became Shadow Chief Secretary to the Treasury. Amber Rudd, Energy Secretary under Cameron has taken over May's old job as Home Secretary. She was only given a front bench job a year ago when she became Secretary of State for Energy and Climate Change.