Support for the Union has strengthened among older people since the last independence referendum, according to a new poll.

The BMG survey for The Herald found that 66 per cent of over-65s opposed independence, while 27 per cent were in favour, 6 per cent did not know and one per cent preferred not to say.

The results mean that those who expressed a view were in favour of the Union 71 per cent to 29 per cent.

Significantly, those who voted No to independence in 2014 were more likely to cast their ballot the same way today than those who voted Yes.

Nicola Sturgeon and Theresa May are due to meet later as part of the Prime Minister's pledge to visit every part of the UK before she files for divorce from the EU on Wednesday.

But the head-to-head is likely to be overshadowed by independence after Mrs May rejected the First Minister's recent call for another vote.

The Scottish Conservatives said that the findings of the poll, carried out before Ms Sturgeon demanded another referendum, showed it was time the SNP “sat up and listened”.

But the SNP said that support for independence was likely to grow as Mrs May’s government continues to pursue an “economically damaging Hard Brexit”, which prioritises control of the UK’s borders over the single market.

Dr Michael Turner, research director and head of polling at BMG Research, said: "Although the headline figure suggests that the vast majority of those Scots aged 65 and over would vote No if another referendum were held today, the figures also suggest that support for the Union has strengthened slightly among older Scots since 2014.

"Just 85 per cent of those who voted Yes in 2014 say that they would vote the same way today, compared to 92 per cent of those who voted No.

"Interestingly it is Yes-Leavers (those who voted for independence in 2014 and to Leave the EU in 2016) who are most likely to have changed their mind, with just 79 per cent saying they'll vote the same way this time around.

"This is compared with almost nine in ten, 89 per cent, of Yes-Remainers (those who voted for independence in 2014, but to stay in the EU in 2016)."

The Greens said that the findings showed that pro-independence parties still had work to do to win over older voters.

Ross Greer, the Scottish Greens’ external affairs spokesperson, added that he was hopeful that Mrs May’s decision to rule out another independence vote before Brexit would demonstrate to over-65s and other voters “the contempt Westminster holds us all in” leading them to “increasingly consider the benefits of putting Scotland’s future in Scotland’s hands”.

An SNP spokesman said that backing for independence was likely to rise as the Prime Minister pursues her ‘Hard Brexit’ strategy “without paying any heed to Scotland’s vital interests”.

He added: "The Scottish Government has a cast-iron democratic mandate to give Scotland a choice as we face up to a Tory hard Brexit. This was a specific manifesto commitment on which the SNP was re-elected just 10 months ago.”

Labour said that the findings showed that pensioners are "rightly worried about the impact of independence".

Scottish Labour deputy leader Alex Rowley said: "The economic case for independence does not stack up and would lead to turbo-charged austerity – further threatening the services that so many older people rely upon.

"Scottish Labour firmly opposes the SNP plans for a second independence referendum which is not in the people of Scotland’s interests. The SNP needs to get a grip on addressing its failings in health, in education and in supporting the Scottish economy and move off this obsession with independence that is having such a negative impact on our country.”

Scottish Conservative deputy leader Jackson Carlaw said: “The older generation know fine well the risks a left-wing chaotic government can pose to the economy.

“That’s why they reject the SNP’s ham-fisted plans for separation in such overwhelming number.

“They appreciate the benefits of Scotland being a key part of the UK, and it’s time the SNP sat up and listened.”

Earlier this month experts suggested that Ms Sturgeon may have jumped the gun on an independence vote.

Commenting on the annual Scottish Social Attitudes survey, which also found record support for independence, John Curtice, professor of politics at Strathclyde University, said that Ms Sturgeon "might have been wiser to have stayed her hand, for on current trends there is a real possibility that demographic change will help produce a majority for independence in the not too distant future anyway.”

BMG Research interviewed 1,362 Scots aged 16 + online between February 23 and 28, of which 561 were aged 65+.