BORIS Johnson launched his bid to become Conservative Party leader with a warning to MPs that they will face "mortal retribution" from the electorate if they try to stop Brexit.

The former foreign secretary presented himself as the one candidate among the contenders bidding to succeed Theresa May who could stop Jeremy Corbyn seizing the keys to No 10.

But at a packed launch event in London, he said it was essential that Parliament now delivered on the 2016 referendum vote and that Britain left the EU, without a deal, on October 31.

His warning came as MPs opposed to a no-deal Brexit prepared to launch a fresh cross-party attempt to take control of the Commons agenda to prevent Britain leaving the EU in the autumn without a deal in place.

"I think maturity and a sense of duty will prevail. I think it will be very difficult for friends in Parliament to obstruct the will of the people and simply to block Brexit," Johnson said.

"I think if we now block it, collectively as parliamentarians we will reap the whirlwind and we will face mortal retribution from the electorate."

Johnson insisted he wanted a "sensible, orderly" departure from the EU but said the country had to be ready for a no-deal Brexit if it was to get the terms it needed from Brussels.

"It is only responsible to prepare vigorously and seriously for no-deal," he said.

"The best way to avoid that is to prepare for it and be absolutely clear to our friends and partners that we are prepared to do that."

He warned that failure to deliver on the referendum result would create an "existential threat" for both Labour and the Conservatives.

"Around the country there is a mood of disillusion, even despair, at our inability to get things done," he said.

"After three years and two missed deadlines we must leave the EU on October 31."

Johnson, who is the front-runner in the leadership race, had to fend off a series of reporters' questions about his past character and record in office.

After Michael Gove's admission that he had taken cocaine in the past, Johnson side-stepped a question as to whether he had also used the drug.

READ MORE: Michael Gove admits to taking cocaine 'on several occasions'

He acknowledged that his use of language – such as his description of Muslim women who wore the burka as letter boxes – sometimes resulted in "some plaster coming off the ceiling".

However, he rejected past charges of untrustworthiness levelled at him by colleagues and rivals.

Referring to his record as mayor of London, he said: "I do what I promise to do as a politician."

Johnson's address is thought to be only the second similar major public speech he has given this year.

In January, the Tory leadership race frontrunner gave a speech at JCB headquarters in Staffordshire and called on the Prime Minister to stop "dithering" over Brexit.

He used the appearance to urge Theresa May to tell the EU that Britain would not accept the controversial backstop arrangement designed to avoid a hard border in Ireland.

According to the register of MPs' financial interests, Johnson has been paid around £284,000 to speak at six corporate events in 2019, where his comments were often picked up by the media.

The MP for Uxbridge and South Ruislip also uses his regular columns in the Telegraph newspaper to intervene in the UK's political debates.

Johnson is expected to be paid £22,917 a month between July 2018 and July this year for the articles, his register entry revealed.