THE launch of the official EU Out campaign in Scotland descended into farce yesterday, after the organisers turned away Scotland’s only Ukip MEP for trying to speak uninvited.

The Vote Leave campaign refused entry to David Coburn after he pitched up at the Grand Central Hotel in Glasgow and threw a strop when he was told he couldn’t take part. One witness said Coburn had been “furious” at the snub.

However, the Remain or In side also had its problems on the first weekend of the EU campaign, after former Tory chancellor Kenneth Clarke said David Cameron “wouldn’t last 30 seconds if he lost the referendum”.

Despite the Prime Minister telling MPs last week that he would stay to negotiate the terms of the UK’s withdrawal if there was a Brexit vote, Clarke said that scenario was “just farcical”.

“We’d be plunged into a Conservative leadership crisis, which is never very edifying,” he said, adding the Tory party would have a “devil of a job” to come together again, however the vote goes on June 23.

London Mayor Boris Johnson attacked Cameron for “shamefully” spending £9.3m of public money on a pro-EU leaflet for every UK household, saying the 14-page document was “not sufficiently absorbent for the purposes” to which some people might like to put it.

Johnson, also criticised Barack Obama for “hypocrisy” ahead of his visit to the UK this week, when he is expected to support Cameron’s call to stay in the EU.

He said the US President had a “perfect right” to comment, but added it was “absolutely bizarre that we are being lectured by the Americans about giving up our sovereignty” when they “would never dream” of sharing theirs with the EU or anyone else.

Speaking in Washington, Chancellor George Osborne said it was the “overwhelming view” of foreign governments and international bodies like the IMF and Nato that the UK should stay in the EU, and warned Brexit could mean higher mortgage rates.

In Glasgow, Scottish Vote Leave director Tom Harris said Coburn had “invited himself to be one of the speakers” at its launch, and threatened to be disruptive when he was refused.

Harris said: “If he wants to get involved in the campaign, I am happy to discuss that with him. But I am not going to be pressurised into giving him a speaker spot at the last minute."

Coburn said he had gone “to wish them well and offer my shoulder to the ecumenical wheel as the established lead voice and only Pro-Brexit elected representative in Scotland. I did then offer to speak at the event, as I thought having someone the Scots had actually elected speaking would help rebalance the event. My offer was declined.”

At the event, Harris claimed pro-Brexit SNP, Labour and Tory candidates in May’s Holyrood election feared speaking out on Europe because they were being “gagged” by their parties.

He said: “A lot of them just don't want to rock the boat and draw attention to themselves. I know there are candidates standing for the Scottish Parliament who feel as I do, that we should be leaving the EU on June 23. But they are inhibited by their own party's [Remain] line on the EU, and don't want to say anything publicly at least until May 5, and possibly not even after that. That is fundamentally undemocratic.

"It is absolutely essential that we have the opportunity to grill our candidates and get an honest answer from them on whether or not they will actually vote themselves to leave or remain. It is not enough to say it is a separate election from the referendum."

Also speaking, Tory Northern Ireland Secretary Theresa Villiers said the EU was “unreformable” and primarily a political project to create a "country called Europe".

Villiers said Britain joined in 1973 in an "admission of defeat" that the country was facing "chronic decline", but it was now time for "self-governing democracy" to return.

"I fundamentally believe we are better off, safer, more secure, more prosperous if this country is outside the EU," she said, claiming Brexit could mean better export deals on whisky.

The Out campaign’s efforts coincided with the SNPs’ two MEPs launching the 'The Wee Bleu Book', a voter-friendly guide to the EU and the the case for staying in it.

The 64-page tract is available free from the website. There is also an initial print run of 2000 hard copies. Authors Alyn Smith and Ian Hudghton said they wanted the book to become the go-to resource for the EU referendum.

Smith said: “My focus, obviously, is the Holyrood election but as I’ve been travelling the country there is no denying that EU stuff is being talked about, so this website is available to all as a resource to get the real facts out there.

"There's a lot of nonsense spoken about the EU, and it’s important not to be distracted from the fact that EU membership is entirely in our best interests and the SNP is enthusiastically backing a Remain vote for the right reasons.

"While it has been produced for SNP activists, I hope the book reaches wider. At least on paper, Scottish politics is broadly united that our best interests are remaining in the EU so while every party will be doing their own thing, if anyone wants to use this I'm delighted."