Cumbria's candidate in the race to become the country’s next Prime Minister says he would authorise the use of nuclear weapons if necessary in a war.

Penrith and the Border MP Rory Stewart also gave clear backing to the county’s nuclear industry, declaring that West Cumbria is the ideal place for it.

In an exclusive interview, Mr Stewart tackled several big issues in the Conservative Party leadership debate.

In recent days, he has emerged as a “rising star” of the contest, achieving more than 43m views with his videos on social media as he toured the country, taking his campaign not to his fellow MPs who control the early stages of selection but directly to the public.

A former professional diplomat, he describes himself as a realist, committed to building a Parliamentary consensus on a form of Theresa May’s deal while rejecting a damaging no-deal Brexit.

Asked about the nuclear issue - including the country’s nuclear deterrent and whether he would ever be prepared to use it - Mr Stewart said: “There’s only one answer, which is yes because this is a deterrent and if people don’t believe you would use it it’s not a credible threat.”

On nuclear power, he said: “I believe in nuclear as a good source of low-carbon energy. I’m not against nuclear power... I think West Cumbria is the ideal place for it.”

Mr Stewart - who says he has had support pledges from enough MPs to stay in the contest after today’s knockout round - warned of dire consequences if the UK crashes out of Europe.

“It would be very damaging for agriculture,” he said.

“Argentinian beef, Brazilian beef, and Irish cheddar would come in tariff free, but if we try to export it to Europe we’d face 40 to 60 per cent tariffs.

“Argentinian and Brazilian beef can be produced for 30 to 40 per cent less. We have been protected from those imports but under no-deal we wouldn’t be.

“Prices would fall and we would see farms going out of business.”

He said Mrs May’s EU Withdrawal Agreement was “a good deal”.

The MP added: “I’d say three things: Firstly, the results of the EU election has demonstrated clearly to MPs how important it is to get Brexit done. Hopefully, some of those who blocked it but were not against Brexit because they wanted a different version would now vote for it.

“Secondly, I’d come in with a fresh mandate.

“And thirdly I have a background in negotiations as a former professional diplomat.”

ITV News political editor Robert Peston tweeted: “He delivered the most coherent and lyrical launch speech of any candidate.

“On this showing the Tories have found a proper star. But they will reject him, because his “moderate” views are out of touch with his party.”

Telegraph sketch writer Michael Deacon said: “In sane times, Mr Stewart would storm this contest.

“These are not sane times.”

Labour Leader Jeremy Corbyn has consistently refused to say whether he would order the use of nuclear weapons in the event of a war. He is a former vice president of the Campaign for Nuclear Disarmament.

In 2015, General Sir Nicholas Houghton told the BBC’s Andrew Marr that refusing to launch nuclear weapons would seriously undermine Britain’s deterrent.