THE difficulties facing the SNP should not mean an assumption the Union is “anything more than temporarily safe”, one of the architects of the Edinburgh Agreement has said.

Professor Ciaran Martin, from the University of Oxford’s Blavatnik School of Government, also said it would be “unwise to bet against” a second Scottish independence referendum or an Irish reunification vote by 2040.

He pointed to reasons including that the use of the “once-in-a-generation” line to argue against holding another vote will be “irrelevant” by the end of the 2030s, as a generation will have passed.

The 45% vote for Yes in the referendum of 2014 had also turned out to be a “floor not a ceiling” for independence, with support remaining sufficiently high that the security of the Union cannot be “taken for granted”, he said.

READ MORE: New Scottish independence poll gives Yes four-point lead over Union

Martin’s comments were made in a new report written for the Institute for Government focusing on “Contested Visions Of The UK’s Future”, which examines issues such as the use of “muscular Unionism” and what constitutional strategies could be pursued.

On the issue of how stable the Union currently is, he said it seems less likely to “disintegrate territorially” than at any time since the Brexit vote in 2016.

He said this is particularly the case in Scotland, where the Supreme Court ruling against Holyrood holding an independence referendum, the departure of Nicola Sturgeon as first minister and the scandals facing her party have left the SNP “in no position to continue to push seriously for an independent Scottish state”.

But he added that it would be “wrong to assume the Union is anything more than temporarily safe, particularly with regard to Scotland”.

“Much of the pro-Union commentary at a UK-wide level of the “it’s over for Scottish nationalism” type seems to mistake the type of commonplace political reversal - such as that experienced by the SNP - with a structural shift in popular support away from independence,” he wrote.

“Polling suggests this is transparently mistaken - independence retains the support of around 48% of Scots, marginally lower than the peak of 2020 but still marginally higher than the Scottish referendum result of 2014.

“The 45% vote to leave the UK in 2014 has proved a floor, not a ceiling, for independence. It is an astonishingly high proportion in historical terms; it is also sufficiently high not to take for granted the continued security of the Anglo-Scottish Union simply because of the current serious difficulties facing the SNP.”

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Martin (above) outlined a series of reasons to suggest that the question of independence will be revived – including that a Labour victory at the next General Election will not be permanent and it is likely the UK will return to the “norm of Conservative-majority governments”.

He also suggested that when the Tories return to office it could be with a more “muscular” approach to the Union.

READ MORE: Steve Baker's Irish vote claim prompts anger over Scottish independence position

Even the “worst-case” scenario for the SNP of losing power in Holyrood in 2026 could be helpful as it would mean the party would not have to account for the “many failings” of government for a period of time, he argued.

And economic conditions could also make it difficult for Labour not only to govern successfully but also to use arguments around healthcare and pensions which the Better Together campaign pushed in 2014.

Martin said that even if none of these things happen, other wider factors will play into the question of independence – pointing to a recent analysis which identified that increased support for Yes over recent decades is down to long-term trends.

He added: “The other factor is the passage of time itself. Since 2014, there has been a dispute as to whether the description of the plebiscite of that year as 'once in a generation' had any standing; by the end of the 2030s, this argument will be irrelevant, as by anyone’s definition, a generation will have passed.

“Analysed this way, while the UK Union has clearly stabilised since its post-Brexit referendum wobble, it would seem unwise to bet against either or both a second Scottish independence referendum or a Northern Ireland border poll by, say, 2040.

“And the UK’s constitutional future will continue to be tested in the meantime.”