Boris Johnson: David Cameron is 'one of the most extraordinary politicians of our age'

The former London mayor, standard bearer for the Vote Leave campaign, said Mr Cameron was a "brave and principled man" who had given "superb leadership".

Giving his reaction to the Leave camp's victory, Mr Johnson insisted that the Brexit vote "does not mean that the United Kingdom will be in any way less united" or "less European".

In a speech at Vote Leave's headquarters in London, he said: "I believe the British people have spoken up for democracy in Britain and across Europe and I think we can be very proud of the result."

Mr Johnson was joined by the other main players in the Vote Leave campaign, Cabinet minister Michael Gove and Labour MP Gisela Stuart.

Giving his reaction to Mr Cameron's announcement, the former London mayor said: "I know I speak for Michael in saying how sad I am that he has decided to step down, but obviously I respect that decision."

Mr Johnson, seen as frontrunner in the race to replace Mr Cameron, paid tribute to him: "I have known David Cameron for a very long time and I believe he has been one of the most extraordinary politicians of our age.

"A brave and principled man who has given superb leadership of his party and his country for many years."

He said it was Mr Cameron's "bravery" that gave the country the chance to vote on EU membership.

"Today, I think all of us politicians should thank the British people because in a way they have been doing our job for us," he said.

"They hire us to deal with the hard questions and this year we gave them one of the biggest and toughest questions of all."

He dismissed suggestions it was "wrong" for the public to have been asked to decide on the issue and said it was "inevitable" that the question should have been decided by the people.

"In the end this question is about the people, it's about the right of the people in this country to settle their own destiny," he said.

Mr Johnson moved to reassure people concerned about the process of Brexit, insisting that there was no need to invoke Article 50 - the procedure which triggers a fixed two-year countdown to leaving the EU.

"There is no need for haste," he said. "As the Prime Minister has just said, nothing will change over the short term except that work will have to begin on how to give effect to the will of the people and to extricate this country from the supranational system."

Despite the geographical divisions in the votes to leave or remain which saw Scotland back continued membership of the EU, Mr Johnson said: "To those who may be anxious, whether at home or abroad, this does not mean that the United Kingdom will be in any way less united, nor indeed does it mean that it will be any less European."