Mayor of London Boris Johnson, a friend of the new Prime Minister from their days at Oxford University, texted his congratulations to David Cameron as he arrived at Downing Street and wished him well in Number 10.

Mr Johnson said: "David Cameron has changed his party and now offers real change for the country.

"Having known him for many years, I know that he has the steel, the energy and compassion to rise to the tough challenges ahead. I wish him well and look forward to working together for the good of London and the UK."