After announcing that Theresa May will become Prime Minister on Wednesday, David Cameron hummed a tune as he headed into 10 Downing Street.brAs David Cameron announced his resignation date he walked away from the podium singing a song before walking inside number 10 Downing Street. Please .brBritish PM heard singing after officially announcing his resignation at a news conference Monday To read more: . »»» Subscribe to .brBritish Prime Minister David Cameron was caught on a live mic humming a tune after he said he will officially resign on Wednesday.