Pete Wishart, who was returned as the representative for Perth and North Perthshire earlier this month with a substantially increased majority, said work was required by the SNP to retain the support which saw it increase its number of MPs at Westminster to 47.

In a blog posted on his website, Mr Wishart added that any talk of “illegal referendums” and “dissolving the union” would see first-time Nationalist voters move away from the party and back to their unionist rivals.

A motion put forward by Inverclyde Council leader Christopher McAleny and MP Angus MacNeil at the SNP conference in October pushed for a “Plan B” - stating that a win for the SNP at the next Westminster or Holyrood election would give the Scottish Government a mandate to open talks on exiting the UK.

Pro-independence supporters march through Edinburgh. Picture: PA

Boris Johnson considers moving civil servants out of London

The SNP has ramped up pressure on the UK Government to grant a second independence referendum following its landslide electoral victory north of the Border.

Nicola Sturgeon has now foirnmally requested the powers from Westminster for another plebiscite - a request that Boris Johnson has repeatedly said he will not grant.

The Prime Minister believes the first referendum was a “once in a generation” event, the result of which must be respected by Nationalists.

Recent polling has seen support for independence marginally up on the 45 per cent achieved by the Yes campaign in 2014, but it has so far failed to climb above the 50 per cent required for a majority.

In his blog, Mr Wishart claimed persuasion is required to win people over to the case for an independent Scotland, and the party must fight the urge to hold a referendum quickly - which he said would play into the hands of the UK Government.

He wrote: “Talk of illegal referendums, UDIs (unilateral declaration of independence), dissolving unions and trying to game or trick our way to independence will send all these aspiring recruits running back into the arms of the union case.

“The Tories are hoping beyond hope that we now blow it through impatience and alienate this new support that is coming our way.

“Instead it should now be all about gentle persuasion, about convincing and understanding.”

He added that a big win for the independence cause in a future referendum would “put it beyond all reasonable doubt and question”.

He said: “There is a real sense that we are in the end game of Scotland’s participation in their union.

“It really now is only ours to lose. We now have the opportunity not just to win it but to win it well and put it beyond all reasonable doubt and question.”

Meanwhile, independence-supporting group Forward As One has set up a crowd-funder to take the UK Government to court if Ms Sturgeon’s request for a Section 30 order is officially rejected.

The campaign, which aims to raise £40,000 to take legal action at the Court of Session, has so far reached just over £9,000.

Writing on the campaign website, Forward As One said: “The aim is simple, to defend the inalienable right of the Scottish people to engage in the fundamental right to vote on the constitutional question without reliance on any politician to ensure that those rights are enabled.”

Yes victory in IndyRef2 requires ‘gentle persuasion’, says SNP MP