Turning the Holyrood 2021 election into an effective referendum on Scottish independence has been suggested as a way forward for the pro-independence campaign by a senior SNP MP following Boris Johnson’s outright rejection of Nicola Sturgeon’s call for indyref2 this year.

The suggestion made by Angus Brendan MacNeil comes as the UK Government prepares to focus on bolstering the Union once Brexit Day passes on January 31 with a Whitehall shake-up that is expected to mean a greater focus on making devolution work better and boosting the constitutional settlement with more public spending announcements for Scotland.

Mr MacNeil said that, while he would have preferred the Prime Minister to have agreed to the First Minister’s demand, his predictably negative response had of itself created political movement.

“It’s very good for the process of independence,” declared the MP for Na h-Eileanan an Iar. “There is nothing like a bit of oppression to get people going. The Scottish Government has to match Boris’s pace now and keep the independence momentum going,” he said.

The First Minister has made clear that she would set out the SNP Government’s “next steps” later this month when it would also ask the Scottish Parliament to again endorse Scotland’s right to choose. Thus far, Ms Sturgeon and her senior colleagues have not ruled out the option of reverting to the courts to try to overturn the PM’s rejection but, given Westminster remains, by law, the constitutional authority on referendums, it is hard to see how a legal challenge could succeed.

Mr MacNeil told The Herald: “There has only been in existence Plan A and now Boris has vetoed it. People are quickly casting around for other ideas.” He suggested two possible ones Ms Sturgeon might consider.

Firstly, to get Holyrood to organise its own “legal referendum” and see if Westminster were to challenge it in the courts; which would undoubtedly be the case.

Secondly, to turn next year’s Scottish parliamentary election into a straight vote on Scotland’s future and that if the SNP gained a majority of MSPs, then this would result in the nation becoming independent.

Mr MacNeil argued that if it was good enough for Mr Johnson to take Britain out of the EU on a vote share of 43 per cent and a majority of Westminster seats at the December General Election, then the same democratic rule should apply to Scotland and that if the SNP secured a majority of Holyrood seats in 2021, this would be regarded as the Scottish people voting for independence.

“The great thing about what Boris has done is that it has provided movement; I thought he would have kept Scotland dangling for a good year. But he has moved the independence process on. We now have to do something to keep things moving,” insisted the Western Isles MP.

Earlier, the PM rejected Ms Sturgeon’s call for a second independence referendum, saying to hold another vote on Scotland’s future would “continue the political stagnation” of the last decade.

In a letter, replying to the one the FM sent before Christmas, Mr Johnson told her: “The UK Government will continue to uphold the democratic decision of the Scottish people and the promise that you made to them. For that reason I cannot agree to any request for a transfer of power that would lead to further independence referendums."

The Tory leader raised his response at the weekly Cabinet, which, his spokesman pointed out, had offered its "full support" for his decision to refuse Ms Sturgeon's request, noting how it had been taken in “close consultation” with Alister Jack, the Scottish Secretary.

“The PM said: ‘This Government has an optimistic vision for Scotland and our whole country in 2020, investing in levelling up in every part of the UK.

"’We do not want the 2020s in Scotland to repeat the previous SNP's lost decade when Scottish schools, hospitals and jobs were left behind because of their campaign to separate the United Kingdom,’" said the spokesman.

But Ms Sturgeon insisted Mr Johnson’s decision had shown “utter contempt for the votes, views and interests of the people of Scotland” and was a strategy that was “doomed to failure”.

She claimed the longer the “Westminster Union” tried to block a referendum, the more support for independence would grow.

“The Westminster Union cannot be sustained without consent. Democracy will prevail. The only question is how long it will take the Tories and the rest of the Westminster Establishment to accept that inevitability,” added the FM.