The impact that Scottish independence would have on England would be "enormous", Andrew Marr has claimed.

The former BBC political editor said he felt London politicians have been "dozing" about the issue of independence, and said they "haven't quite grasped how big it is".

His comments came ahead of his appearance in the 2020 online Wigtown Book Festival next week, where he is set to discuss Scottish independence and the Elizabethans.

"We are coming to a period where it’s perfectly possible that Scotland will leave the United Kingdom," he said. "We have left the EU. There are lots of fundamental questions we are asking about ourselves.

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“When the Queen dies it will be a tremendously traumatic moment for a lot of people. I think it will cause the British to look again at themselves.”

Marr, who was born in Glasgow and went to school in Dundee and East Lothian, admitted he believes the biggest story in British media over the next few months and years is likely to be independence.

He said: “If you look at the opinion polls at the moment, the independence side has quite a clear lead. There seems to be an energy and a sense of purpose in the SNP. They have their own troubles, a lot of internal arguments and I am not someone who believes in ideas of manifest destiny and inevitability.

“All we can say at the moment is that the SNP are ahead and they seem confident – and if we go through a very hard Brexit that will probably help the SNP.

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“In my view London politicians of all parties have been dozing about this issue. They haven’t quite grasped how big it is. If it happened the impact on England would be enormous. What’s the country called? What’s the territory? What’s the flag? How does it defend itself? All these things.

“It’s a very, very big deal indeed. I don’t think they have focused on it or come up with any way to address it. I think it’s going to be the big story of the year ahead.”

Marr will speak at this year's Wigtown Bok Festival on Tuesday, September 29, at 11am.

Other speakers include novelist AL Kennedy and historian Neil McGregor.