Scottish independence would not be triggered by the UK accidentally crashing out of the European Union, according to the Scottish Secretary David Mundell.

Scotland's only Tory MP rejected suggestions that Scotland would leave the UK "in a heartbeat" if Britain voted to quit the EU.

And he suggested that any second independence referendum would have to wait for at least 15 years, if not an awful lot longer, in an interview with the Herald.

His comments follow predictions from Blair Jenkins, the Yes campaign chief, that there will be another independence vote within the next six years.

First Minister Nicola Sturgeon has suggested that the UK leaving the EU would be grounds for a second referendum.

David Cameron has pledged to hold an In/ Out referendum by 2017 at the latest.

But Mr Mundell rejected Nick Clegg’s famous prediction that if the UK Government loses that vote it will also lose Scotland.

While still Deputy Prime Minister Mr Clegg predicted that Scotland would become independent "in a heartbeat" if the UK left the EU.

Mr Mundell said: "Nick Clegg’s analysis on many things has not proved to the case. I like Nick Clegg as a person but his political analysis is not something I place great weight on”.

A poll earlier this month suggested that a so-called 'Brexit' may be more likely than previously thought.

The Survation poll found that public opinion against the EU has hardened in recent months, with 51 per cent of those who said they knew how they would vote backing 'Brexit'.

Membership of the EU was a major bone of contention during last year's independence campaign.

Senior pro-union politicians argued that one of the benefits to membership of the UK was that Scots would not find themselves outside the EU, even for a small period.

That claim was furiously denied by SNP politicians who argued that other European leaders would never accept an independent Scotland outside the union.

Mr Mundell also disputed Ms Sturgeon's claim that a "generation" could last as little as 15 years.

In the run up to last year's vote senior SNP figures described it as a "once in a generation" and a "once in a lifetime" opportunity.

Mr Mundell said: “The SNP want to tell us what people in Scotland think and what the rules and the term and conditions are – that is not for them. It’s not for us to get into these sort of definitions."

However, he added: " I don’t think most people would regard a generation as simply being 15 years. And certainly I hope a lifetime is not 15 years, that would be rather worrying for us all."

He also suggested that events surrounding last year's vote created a "unique intensity" that pro-independence supporters would find difficult to replicate.

He said: "For the first time in most people’s lives (there was) a binary choice and a very significant difference in what the outcome would mean along with the level of emotion and commitment that were put in by both sides in terms of the effort made.

“For me the referendum was characterised by the level of street activity, public meetings of a nature that you had not seen in a generation and sheer doorstep contact.

“I think that is a positive environment for engagement and that is why we had such a huge turnout that we did”.

However, he pointed out that voter numbers fell significantly just eight months later at May's General Election, although they were still relatively high.

"Maintaining that intensity (seen in the referendum) is not going to be something that is easily achievable," he said.

In his opinion a sign of the problems that hurt the Yes campaign could be when thousands of people protested outside the BBC days before the election when they could have been working to win over undecided or No voters.

He said: "I think one of the mistakes the Yes campaign made was an attempt to say for sure that everything would be better. Because they could never, ever quantify or confirm that."

Asked if he thought the result could have been closer , he said: "There's always the ability to look back in retrospect at elections and see what could be different.

“Certainly if I had been involved in the Yes campaign I would not have had thousands of people outside the BBC before the vote, I would have had them round knocking on people’s doors.

“But these are matters that are always open to speculation.

“The thing is we have had the referendum. People have voted. That is the outcome that mattered."

Mr Mundell is due to make a speech in Edinburgh later this week on the benefits of Scotland remaining in the UK.

He will argue that it is "clear Scotland made the right decision" last September.