SNP MPs are being warned that if Westminster is given a veto over Brexit it could exercise a similar sanction over independence following indyref2.

The warning from former party leader Gordon Wilson is directed at those MPs who want a vote on the UK’s exit from Europe given to the two Houses of Parliament.

“Be careful of the dangers of giving Westminster a veto over Article 50 and the subsequent negotiations,” says Wilson. “If you do, it will create a British parliamentary precedent for blocking the outcome of the next Scottish independence referendum.

“Veto Brexit and Westminster will veto independence – nothing is surer. This precedent will be cast in your face and you will have no moral authority to object.”

Wilson, right, who now runs the political think-thank Options for Scotland, said the SNP should consider the potential consequences of a Westminster veto and reminded MPs that the Lords was also part of Westminster.

He says: “The Lords should be given no say in countering the will of the people expressed in a referendum. It would take the constitution of the UK back to the 18th century.

“As a former MP, I know the frustrations you face. But I am disturbed by the lack of strategic thinking. Looking after Scottish interests is one thing, queering the pitch for independence is another.

“If Brexit in Scotland is to be challenged, it must be through the elected Scottish Parliament in which Scottish sovereignty is vested.”

His comments come as a new poll suggests an independent Scotland within the EU is the most “ideal scenario”.

The Panelbase poll for The Sunday Times and English radio station LBC saw support for independence down four points from 52 per cent in June in the aftermath of the EU vote, but up three points from the 2014 referendum result.

Scots also remain split on support for a second referendum and there is no clear support for any of the constitutional options on the table.

Nearly half (46 per cent) oppose a referendum in the next few years, 33 per cent want indyref2 before Brexit negotiations have concluded and 21 per cent want a re-run after the Brexit talks.

A third want independence within the EU, more than a quarter (28 per cent) want both EU and UK membership, less than a quarter (23 per cent) back remaining in the UK after Brexit and 11 per cent want independence outside the EU.

First Minister Nicola Sturgeon said the Brexit vote was “probably the most striking and significant instance ever” of the “democratic deficit that Scotland has continually faced”.

Writing in the Sunday Herald, she said: “Such a lack of control over our own future should be of concern to everyone – no matter how they voted in June.”

Former first minister Alex Salmond predicted that another independence referendum would be held in autumn 2018.

Also in the Sunday Herald, he wrote: “Our deadwood unionist media (have) wheezed that support for independence was ‘only at 48 per cent’. Only 48 per cent? When I fired the starting gun on the 2014 referendum support for independence was at 28 per cent!”

The SNP has launched a “new national conversation” on Scotland’s future, with activists urged to speak to two million people before the end of November.

SNP business convener Derek Mackay said: “Every poll conducted since June 23 has shown support for independence ahead of where it was in September 2014 – and that is before the impact of Brexit starts to hit home.”

Scottish Conservative economic and finance spokesmen Dean Lockhart and Murdo Fraser have written to the First Minister over what they described as continuing uncertainty.

Scottish Labour leader Kezia Dugdale said “it makes no sense to return to the arguments of our past”. Scottish LibDem leader Willie Rennie blasted former prime minister David Cameron over his handling of the indyref1 aftermath.

Speaking at his party conference in Brighton, he said: “David Cameron says he loved Scotland but everything he did after the referendum in 2014 undermined the Union.”

The Scottish Greens used the second anniversary of the referendum to launch a new campaign called No2Yes to encourage No voters who have become independence supporters since 2014 to share their stories.