South West Herts MP David Gauke says he believes there are "parliamentary mechanisms that could prevent a no-deal Brexit.

But the Justice Secretary, who has made clear he would not serve in Cabinet under Boris Johnson, said that would "not necessarily" involve bringing down a Johnson administration, he said.

Mr Gauke stressed that he would not vote against a Tory government in a motion of no confidence if it was heading towards a no-deal Brexit, but told BBC Radio 4's Today programme: "I don't think it will come to that. I think that there will be parliamentary mechanisms, if you like.

"There is a clear majority in the House of Commons that doesn't want to leave the EU without a deal, I think that will become very clear in the autumn."

He added there was the possibility of a "period of huge uncertainty" in Westminster as the October 31 deadline approaches.

"Are there circumstances where there is a risk of a government losing a confidence motion? Yes, clearly there are circumstances where there is a risk that that might happen.

"I think that the new prime minister would be wise to avoid getting into those circumstances."

Tory leadership hopeful Jeremy Hunt arrived back at his residence after a run at about 7.10am.

When asked how he felt about today, he said: "All to play for."

Boris Johnson entered his campaign headquarters in Westminster at just after 8am.

Asked if he agreed with Mr Hunt that it was still all to play for, Mr Johnson said: "All to play for."

Mr Hunt left his residence on foot at around 8.20am and said he was walking to work.

He said he was not doing any interviews, adding that there will be plenty of chances for talking later.

Asked if he thinks he has won, he replied: "Who knows?"

And asked if he knows who has won, he said: "No, I don't."

Asked if he is feeling positive, he replied: "I'm feeling very positive, but who knows what's going to happen?"

Mr Hunt was asked if he would serve under Boris Johnson and he said: "All to be seen. Let's wait for the result."

Former defence secretary Sir Michael Fallon claimed Boris Johnson's optimism and fresh mandate would help shift Brussels towards a deal.

He told BBC Radio 4's Today programme: "Nobody is aiming for no-deal, that is not the strategy. We want a better deal, Parliament wants a better deal, and Boris Johnson has made clear throughout that he wants a better deal.

"But the way to get a better deal is to be very firm that that date is there in law.

"There are three months now before the end of October and it is perfectly possible, with plenty of goodwill on both sides, to improve the agreement so that Parliament does, in the end, support it."

He added: "Let sunshine win the day. Boris is optimistic about this, he is ambitious about this. We have three months to get wording that Parliament will approve.

"I think you will find that a new government, a new mandate which Boris, I hope, will get this morning, a new focus, new ministers in charge, a fresh negotiating team - I think you will find that Brussels will not be unwilling to say 'OK, what are the points that you need to satisfy Parliament on?'."

Green MEP Philippe Lamberts, a member of the European Parliament's Brexit steering group, said Boris Johnson - if he wins the Tory leadership race - "will be confronting the exact same situation as Theresa May".

The Belgian MEP told BBC Radio 4's Today: "Boris Johnson is known to want many things and often contradictory things like having your cake and eating it, he is on record saying that.

"So indeed he wants good relations with the European Union and he wants to be able to cut off all ties and not have the Irish backstop and all the rest of it."

He suggested that Mr Johnson should seek to pass a Brexit deal with a Northern Ireland-only backstop, something which would lose the support of the DUP but could pick up support from elsewhere in the Commons.

"If I were Boris Johnson I would do just that and then call for a general election which I think he could then win having delivered a form of Brexit," he said.

Ministers including Karen Bradley and Jeremy Wright have arrived at Downing Street for a cabinet meeting.

Matt Hancock is among ministers who have arrived at Number 10.

Mr Hancock was followed by Jeremy Hunt and Liz Truss.

When asked if he would serve under Boris Johnson, Rory Stewart replied: "No."