As a global city and leading international financial centre, London is at the heart of Britain’s economic success. So the victory of the Conservative candidate in the capital’s mayoral election in May was widely seen as an augury of success for the UK opposition at the next general election. However, Boris Johnson’s first few weeks in City Hall have raised disturbing questions about the fitness of the Tories for office.

Most revolve around Mr Johnson’s choices in appointing his senior management team. Seven weeks after his election, he parted company with a political adviser who had suggested that Caribbean immigrants should be allowed to go home if they did not like London under the new mayor. Two weeks later, Ray Lewis stood down as a deputy mayor following allegations of sexual and financial misconduct. This week, Mr Johnson lost another deputy mayor in Tim Parker, a former private equity executive who was chief executive of the Greater London Authority and about to take charge of London’s public transport.