David Cameron forgets to turn his mic off while humming

The UK Prime Minister David Cameron will be leaving 10 Downing Street on Wednesday - nine weeks earlier than planned after another breathtaking day in Westminster saw the Tory leadership contest cut short.

He set out the timetable for handing over the No 10 keys to Theresa May, who was announced the new Tory leader after her rival Andrea Leadsom pulled out of the race.

Bizarrely, the outgoing Prime Minister was then caught on microphone humming a tune as he walked back into Number 10, The Daily Mail reports.

'On Wednesday I will attend the House the Commons for Prime Minister's Questions and then after that I expect to go to the Palace and offer my resignation, so we'll have a new prime minister in that building behind me by Wednesday evening,'  he said, adding "doo, doo, doo, doo. Right...Good".