Boris Johnson bows out

Former mayor of London Boris Johnson yesterday ruled himself out of the race to succeed Prime Minister David Cameron on a day of high drama following Britain's shock vote to leave the EU.

The decision by Johnson, who spearheaded the "Leave" campaign, upended the Conservative Party leadership contest and added to deep uncertainty over how and when the country will split from the bloc.

Johnson had been tipped as a favourite to succeed Cameron, who resigned after the June 23 referendum saying he would leave it to his successor to begin formal talks with the EU on Britain's departure -- despite European leaders insisting on a quick divorce.

The favourite to take over from Cameron is now interior minister Theresa May, who supported staying in the EU but insists she would honour the outcome of the referendum if she won.

Johnson made his announcement a couple of hours after fellow Brexit campaigner Michael Gove announced his own surprise bid for the top job, sharply criticising his mop-haired former ally.

In a statement that one MP likened to the actions of the murderous Macbeth in Shakespeare's play, justice minister Gove said Johnson "cannot provide the leadership or build the team for the task ahead".

After listing the qualities required in Britain's new leader, Johnson left the punchline for the end.

"Having consulted colleagues and in view of the circumstances in parliament, I've concluded that person cannot be me," he told shocked supporters at a press conference in a London hotel.

"Time is not to fight against the tide of history," he added.

Observers were left stunned by the dizzying events in the corridors of power, where opposition Labour leader Jeremy Corbyn is also clinging on to his job after a revolt by MPs.

"It looks a bit like House of Cards and may be too many politicians are watching Game of Thrones at the moment," health minister Jeremy Hunt told SkyNews.

May insisted that "Brexit means Brexit" as she launched her campaign. May said she would not trigger the formal process for leaving the EU known as Article 50 until next year.

Gove, meanwhile, wants Britain to quit the European single market. He suggested during the campaign it could take at least four years to leave the EU.

There are a total of five candidates in the race to be Conservative leader, who will automatically become PM. They will be whittled down to two by a series of ballots by Conservative MPs in the coming days before being put to a vote of grassroots party members. The new leader will be announced by September 9.