Chief Vote Leave campaigner Boris Johnson attempted to strike a unifying tone as he delivered his victory speech, a day after the UK backed a Brexit at the 23 June EU referendum. The former mayor of London, joined by Vote Leave chair Labour's Gisela Stuart and Justice Secretary Michael Gove, made the sombre speech just hours after David Cameron announced his intentions to resign as prime minister.

Johnson paid tribute to the Conservative leader as the "one of the most extraordinary politicians of our age", while trying to reassure Remain backers, particularly young voters, that the UK would be more prosperous outside the 28-nation bloc.

Johnson went onto attack the EU as being "too remote, too opaque and not accountable enough" and urged Cameron not to trigger Article 50, which would start the UK's formal process to leave the political and economic union.

"There's no need for haste and, as the prime minister has said, nothing will happen in the short term," Johnson said. He added: "I believe British people have spoken up for democracy in Britain and across Europe."

Cameron, who was a prominent figure in the Remain campaign, said he wanted a new Conservative leader to be in place by October. "I will do everything I can as prime minister to steady the ship over the coming weeks and months but I do not think it would be right for me to try to be the captain that steers our country to its next destination," he said, in an emotional address outside Number 10.

"This is not a decision I've taken lightly but I do believe it's in the national interest to have a period of stability and then the new leadership required. There is no need for a precise timetable today but in my view we should aim to have a new prime minister in place by the start of the Conservative Party conference in October.

"Delivering stability will be important and I will continue in post as prime minister with my cabinet for the next three months."

He added: "Britain is a special country – we have so many great advantages – a parliamentary democracy where we resolve great issues about our future through peaceful debate, a great trading nation with our science and arts, our engineering and our creativity, respected the world over.

"And while we are not perfect I do believe we can be a model for the multi-racial, multi-faith democracy, that people can come and make a contribution and rise to the very highest that their talent allows.

"Although leaving Europe was not the path I recommended, I am the first to praise our incredible strengths."

Bookmakers William Hill have installed Johnson as even-money favourite to become the next leader of the Conservatives, cutting his odds from 11/4, making Home Secretary Theresa May 7/2 second favourite and Gove third at 9/2.