Former SNP MP's Indyref Tube plan branded 'unhinged'

Mr Kerevan, who was MP for East Lothian from 2015 to 2017, also said the First Minister could hold a snap Holyrood and break Treasury rules in a “strategy of tension” .

Independence would not be a “neat constitutional process” but a “political and social revolution” involving “political and economic convulsions”, he said.

He said a wildcat, illegal referendum may be needed in the last resort.

The Scottish Tories called the comments “unhinged”.

The SNP distanced itself from the remarks.

With Theresa May refusing to grant Holyrood referendum powers and splits in the Yes movement over timing, Mr Kerevan set out a plan for obtaining Indyref2 by other means.

Writing for the pro-independence Bella Caledonia website, he said Brexit showed the British state was “falling apart under its own contradictions”.

He said: “There never was a more immediate need for Scotland to exit this dysfunctional economic and political setup by calling a second independence referendum as soon as possible. With the British ruling elite distracted by its own problems, now is the optimal time to strike for Scottish freedom.”

Since the SNP losses in the last general election, Nicola Sturgeon has moved cautiously on the timing of another referendum, repeatedly delaying an updated timetable.

Other senior SNP figures have also suggested moving gradually to build support among the soft No voters of 2014, as they are the swing voters vital to securing a Yes next time.

However Mr Kerevan said people should recognise that “winning an independence majority can no longer be premised on a strategy of molecular acquisition”.

He said: “In the present critical moment, you will not get over the 50 per cent barrier using uber cautious appeals to individual self-interest – folk are too frightened and uncertain.

“Nor will presenting independence as a ‘minimum change’ option (pace the so-called Growth Commission) allay these fears.

“Instead, the independence message must be collective. It must be radical, popular, transformative and mobilise the mass of working class voters and young people.”

He went on: “It is certain - in the current Brexit crisis - that the Tory government in London will refuse to agree a fresh referendum and veto a new Section 30 Order [devolving temporary referendum powers].

“This refusal must be met by a phased escalation of public civil disobedience and Westminster parliamentary obstruction by SNP MPs.

“Civil disobedience should be peaceful but inventive; e.g. blocking the London subway in the rush hour. The SNP government at Holyrood should rally public support by challenging Treasury control over the Scottish budget; e.g. by breaking Treasury spending rules to subvert the welfare cap.”

He said that if London still refused, Ms Sturgeon should attempt to engineer an extraordinary Holyrood election, on a mandate to seek immediate independence negotiations.

“If an independence majority is elected but negotiations refused, the SNP should withdraw its MPs from Westminster, and declare a sovereign assembly on the lines of Dáil Éireann in 1919 (with a confirming plebiscite to follow immediately).”

He said if that route also failed, Ms Sturgeon should hold a Catalan-style referendum as a last resort “even if Westminster refuses to recognise its legality”.

Scottish Tory chief whip Maurice Golden said: “This is an unhinged and ridiculous intervention on the debate. Political figures are supposed to be leading by example and encouraging good behaviour, particularly after years of division and appalling abuse.

“Instead, this former SNP MP wants to bring Britain’s capital to a standstill if he doesn’t get what he wants. If the Yes movement is a remotely responsible one, it would distance itself from both Mr Kerevan and his comments.”

LibDem Scottish Affairs spokesperson Jamie Stone MP said: “This strategy sinks to even lower depths than usual. George Kerevan seems to have got off somewhere between Barking and Turkey Street. If he wanted to cause service disruption on ScotRail it wouldn’t work because people wouldn’t be able to tell the difference.”

An SNP spokesperson said: ““This is not the SNP’s position. There is a cast-iron mandate to give the people of Scotland a choice over their future.

“And there can be no clearer demonstration of the need to take all decisions for ourselves in an independent Scotland than the chaos of Brexit.”

Mr Kervevan, a former member of the International Marxist Group, is due to take part in an event organised by the Scottish Socialist Party in Edinburgh on Tuesday.

He is due to appear alongside former Socialist MSP Colin Fox at an event called ‘Brexit, independence and the case for socialism’.

Gerry Carroll, a Northern Ireland Assembly member for the People Before Profit Alliance, will also take part.

Mr Fox said: “While the Brexit drama dominates the scene working people face continuing austerity and the worst fall in wages since the Battle of Waterloo. Health, housing and public transport are all in crisis but barely mentioned.”

“The SSP believes that none of these problems will disappear whether we are in the EU or not. History shows that it is only when working people stand up for themselves that meaningful change happens.

“Independence offers an escape from the brutal free market failures embraced by both the UK and the EU.

“That is why we back an independent socialist Scotland, a modern democratic republic and believe that the Yes campaign needs to show how Scotland’s working class majority will be better off with independence.”

“Each speaker at the meeting will explain how the socialist ideas of solidarity and collective action are more vital than ever to defend and advance the interests of Scotland’s working class majority”