Boris Johnson refused to commit to bringing down Britain’s net immigration levels if he became Prime Minister while Jeremy Hunt insisted he would do, saying a failure to do so would be a “betrayal” of the 2016 referendum.

In the final head-to-head hustings, which covered Brexit, tax, their background but once again failed to touch on the Union, Mr Johnson was asked whether or not migration numbers would fall under his premiership.

He insisted he was “not going to get into some numbers game” but stressed: “What we will have is control, which is what the people voted for and it's high time we got it."

Mr Hunt said he agreed about taking back control but noted: “That's what people voted for but they also voted with an expectation that overall levels of net migration would come down and people would think we were betraying the spirit of that Brexit referendum if we didn't find a way of bringing down overall numbers.

"The way that we do it, though, is what I did in the NHS, which is by increasing the number of doctors and nurses that we train in this country so we don't need to bring in so many from other countries.

"So, it's boosting the education and skills levels of our own people that's the right way to do it," he argued.

The two contenders again clashed on Brexit during the event hosted by The Sun.

Mr Johnson insisted there was enough time to get Brexit “over the line,” insisting there was too much pessimism and he was confident the EU would respond to “clarity of purpose”.

Declaring how the country must prepare for a no-deal outcome, he said: “I don’t think we will carry any conviction with our friends and partners over the Channel unless they look into our eyes and see we are absolutely determined to come out of the EU on October 31 come what may and that’s what I will deliver.”

Mr Hunt said he was just as passionate to come out of the EU by October 31 but he claimed his rival was promising things about Brexit and trade deals which he could not deliver if he were to enter 10 Downing St.

"Right now, Boris is guaranteeing something that he knows that neither he nor I can truly guarantee because we don't know what Parliament would do.

"We do not have a majority in Parliament. We can hope and I would hope and urge my colleagues not to take no-deal off the table.

“It is one of the most dangerous and destructive things we can do when we are trying to get a deal but we cannot control what Parliament does," declared Mr Hunt.

But Mr Johnson challenged his colleague on when he would deliver Brexit, saying any delay would be "absurd".

"I'm hearing that Jeremy might delay for a few days. Well, how many days? Is that three days? Is that six days? You said you would be prepared to wait until Christmas. Which Christmas is it?" he asked to laughter from the audience.

On the Irish backstop, both contenders said it had to go and that tweaks here and there would not be enough. They made clear they would not accept a five-year time limit or a unilateral exit clause.

Mr Hunt spoke of technical solutions, which, he said, Brussels had accepted in the long term but not in the short term because it wanted to keep Britain in the customs union for the foreseeable future.

Mr Johnson agreed and argued that the issue of solving the border should be remitted to the process of a post-Brexit trade deal.

The candidates were asked to comment on the racism row engulfing Labour and if Jeremy Corbyn was anti-Semitic.

To applause, Mr Hunt replied: "Unfortunately, he may be," while Mr Johnson noted: "By condoning anti-Semitism in the way he does, I am afraid he is effectively culpable of that vice."

On income tax, the former London Mayor said he found it strange that people had criticised his plan to cut taxes for middle and high earners.

"I do think it is a bit odd that there's been so much controversy. When you consider that there are police inspectors, there are senior nurses, there are heads of maths departments who are now being captured paying the higher rate of tax."

He continued: "I'm one of those that people basically should wherever possible be able to spend their own money as much as they can."

However, Mr Johnson was unclear over whether it remained a policy or a subject for debate.

Mr Hunt warned against the public viewing the Tories as a party for the rich and privileged when it came to taxes.

“It's very important that we don't inadvertently play into the message that Jeremy Corbyn so wants to project about our party," he added.

In other developments:

*Stephen Barclay, the Brexit Secretary warned the winner of the Tory leadership contest that "many MPs" would work to stop attempts to depart the EU without deal;

*Tory backbencher, Sir Oliver Letwin, the former Cabinet Officer warned that any attempt by the next PM to suspend Parliament to force through a no-deal Bx would likely mean the issue would end up at the UK Supreme Court;

*former minister and anti-Brexit Tory MP Guto Bebb announced he would not stand at the next election, complaining the Tory Party was now intent on appealing to English Nationalism.