UKIP is plotting to exploit a "nodding dog" mentality at Holyrood over the UK's membership of the EU in a bid to win its first ever MSPs.

David Coburn, the party's only elected politician north of the border, said that he believes his party will win at least five MSPs in May as advocates of an out vote from mainstream parties expressed fears that a leadership vacuum in a Scottish leave campaign will play into Ukip's hands.

It comes as Conservative MSP Margaret Mitchell became the first Holyrood politician to back leaving the EU. However, she admitted that she could yet be persuaded to back an in vote and Tory strategists confirmed that she would not be "leading the charge" in Scotland to leave.

Jim Sillars, the former SNP deputy leader who is openly backing an EU exit, said that figures such as Nigel Farage and Boris Johnson should stay south of the border during the campaign as they do not have currency with Scottish voters.

He said that he would take part in debates on the issue when asked and is planning on setting up a small organisation to advocate a leave vote to those who back Scottish independence. But he said that, at 78, he is too old to become a figurehead of a wider campaign. He added: "I don't really see that anybody will take a leadership role in Scotland, but I hope that someone does emerge.

"There is a genuine concern for people on the left that if the only opposition to the SNP is Ukip, then that's to the advantage of Ukip as they will get most of the publicity. I hope that someone from what I regard as a much more mainstream position than Ukip will lead the argument."

While polls have consistently predicted that Scotland will vote to stay in the EU overall, around 30 per cent want to leave meaning that if even a small proportion backed Ukip the party could expect to return several MSPs due to Holyrood's proportional representation system.

With the EU referendum to take place on June 23, just weeks after the Holyrood election, Ukip are set to enjoy significant publicity in the run up to the Scottish Parliament vote.

Mr Coburn, who saw his party take less than one per cent of the regional vote in 2011 but more than 10 per cent in Scotland in the European elections three years later, said he believed the Scottish Parliament was full of "nodding dogs" who went along with their leader's position and that Ukip would benefit as a result. A recent poll put the party on six per cent support.

He said he did not see himself leading a Scottish out campaign but would instead act as an "anchor" for anti-EU voices from across the political spectrum, describing a recent George Galloway speech on Europe as "fabulous".

The MEP, who yesterday blamed EU regulations for difficulties with his toaster, added: "People want to see someone get in there and shake it all about. I hope to be doing the hokey cokey in the Scottish Parliament. Ukip will be a fresh wind blowing through Holyrood, saying things nobody else dare say. It's like 1984 up here with all the thought speak which is very, very worrying.

"The SNP leadership wants to be swanning around the chancellories of Europe, with Angela Merkel and François Hollande. They want to swank about but none of the SNP members want that and many are going to give their second vote to Ukip.

"I hope for five MSPs, but I would love seven or even more. We're saving ourselves for a big campaign. There will be a big blast to come."

A senior Scottish Conservative source said the party would be focusing on the Holyrood elections rather than the EU and was "pretty relaxed" about the prospect of Mr Coburn appearing more often on TV.

He added: "Ukip in Scotland are a marginal force. We're not worried about them. We have MSPs on the in and out sides and that reflects our membership."

No Labour MSPs have yet backed an out vote, although they will be free to do so if they wish. Nigel Griffiths, a former Edinburgh MP, has set up a Scottish Labour leave campaign although it is yet to attract significant publicity.