BORIS Johnson has urged Britain to “come with us” to get Brexit done and avoid the “horror show” of a Jeremy Corbyn-led Government that would help the SNP break up the Union.

After visiting Buckingham Palace where the Queen agreed to formally dissolve Parliament, the Prime Minister marked the official start of the General Election campaign from behind a lectern in Downing St and accused the Labour leader of “doing a deal” with Nicola Sturgeon to fracture the UK to ensure there would be not one but two referendums next year: on EU membership and Scottish independence.

Gesticulating in front of the famous black No 10 door, Mr Johnson said there was a straightforward choice on December 12.

“Come with us, a government that believes in high wages and is raising the living wage to £10.50, the biggest ever increase or go with a left-wing Labour Party that believes in high taxes for everyone and voted against £7,800 of tax cuts on working people.”

After highlighting differences between the Tories and Labour on education, immigration and foreign policy, the PM declared: “Come with us and get Brexit done and take this country forward or, this is the alternative next year, spend the whole of 2020 getting a horror show of more dither and delay.

“Imagine waking up on Friday December 13 and finding Corbyn at the head of his technicolour rainbow coalition.

“They would spend the whole of 2020 having two referendums; one on Scotland - because he has done a deal with the Scots Nationalists to assist the break-up of the Union to sustain him in power - and another referendum on Brexit, which is supposed to happen in nine months’ time after he has renegotiated, supposedly, this deal.

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“What is his plan for that renegotiation? What question would be put to the public? We don’t know. What are the options? We don’t know. We don’t even know what side he would take. We don’t know what would happen if the result was either for Remain or Leave. Best of three? Call it quits? We don’t know.

“What we do know is that in any scenario the dither, drift and delay, which is increasingly damaging to our country would just continue.

“There is only one way to avoid that nightmare and that is to vote for a compassionate, One Nation Conservative government,” insisted Mr Johnson, who is due to deliver a similar message at an opening rally this evening in the Midlands before heading to north-east Scotland tomorrow for a campaign visit.

Earlier, the Tory leader claimed it was “frankly mindboggling” that MPs, having passed the Government deal, then voted to delay it. If the old Parliament had had its way, then Britain would not leave the EU at the end of January, he argued.

The PM stressed that further delay would not only be bad for democracy but also for the economy as it would create more uncertainty.

“If we can get this deal over the line with a sensible majority government, we certainly can, then we can release that pent-up flood of investment. Hundreds of billions are waiting to pour into the UK and we can inject a surge of confidence into our system.

“And we in this government can get on with delivering on the priorities of the people.”

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Mr Johnson admitted that he did not want an election, particularly in December, but stressed that it was the only way to get passed a “paralysed” Parliament to create a new one so that the voters’ mandate of 2016 could be honoured.

“I can tell you I got to the stage where I wanted to chew my own tie in frustration because in a sense we are so nearly there,” he declared.

Again, the PM insisted there was an “oven-ready” deal, by which the UK could leave the EU in just a few weeks.

“It’s a great deal for this country. It delivers everything I wanted when I campaigned for Brexit.

“We can not only take back control of our money; yes, we’ll be able to spend hundreds of millions every week on our priorities such as the NHS; we can take control of our borders with an Australian-style points-based system, so we can attract the works from scientists to agricultural workers that our economy actually needs; and we can take back control of our laws so we can do things differently and better if we choose from free ports to free trade deals, from banning the cruel live shipment of animals to cutting VAT on sanitary products.

“We can leave the EU as one UK, whole and entire and perfect as we promised,” he added.