THE SNP’s Westminster group is split over whether or not to back John Nicolson as he faces a parliamentary probe into his conduct.

The Ochil and South Perthshire MP was referred to the Privileges Committee for investigation on Tuesday after a majority of MPs voted in favour of the move, but only a third of SNP MPs voted against.

Speaker Sir Lindsay Hoyle said Nicolson gave a "partial and biased account" of a letter sent to him on Twitter which caused a social media “pile on” over his decision not to refer former culture secretary Nadine Dorries to the same committee Nicolson will now face himself.

READ MORE: SNP's John Nicolson to face investigation after Speaker letter row

Nicolson had summarised the correspondence between himself and Hoyle in a short video clip, which prompted the probe over his conduct as the letter was confidential.

Hoyle granted David Davis, Tory MP and former Brexit minister, permission to lodge the motion on Nicolson on Tuesday afternoon, to be heard the next day.

While none of the SNP MP’s voted against Nicolson, as 371 parliamentarians from the Tories, Labour and LibDems did, 26 of the group did not record a vote in the House of Commons debate.

This included the group leader Ian Blackford, chief whip Owen Thomson, deputy leader Kirsten Oswald and numerous other shadow cabinet members.

The National: Blackford did not record a vote in the Commons debate on Tuesday afternoonBlackford did not record a vote in the Commons debate on Tuesday afternoon

Only 16 out of 44 SNP MPs voted against the motion, just over a third (36%). One group insider claimed that Nicolson is not popular within the Westminster branch of the party.

Meanwhile, others declined the opportunity to express their support for Nicolson as he is poised to go through the investigation process.

However, those in the party who have shown Nicolson support hit out at the heavy-handed move.

Pete Wishart, SNP MP for Perth and North Perthshire, who intervened in the debate to point out that he was unaware of the rule that all correspondence with the Speaker is confidential despite 20 years in the Commons, said that the incident was an exercise in “institutional bullying”.

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He told The National: “He [Nicolson] could have easily apologised and moved on, but he genuinely didn’t feel he had anything to apologise for.

“He said sorry for upsetting the Speaker but on the substantive issue of breaking any rules, he was totally unaware.

“I had absolutely no doubt whatsoever that it [the motion] was going to pass.

“For us [SNP] you want to make sure rules are respected, but the Tories ganging up on him the way they did today, this wasn’t about rules, it was retribution and revenge with the full force of Parliament.”

Wishart also pointed out that Nicolson will now face the same committee which investigated Owen Paterson’s outside earnings and Boris Johnson’s partying in Number 10 while the rest of the UK lived under strict lockdown rules imposed by his administration.

The National: Wishart defended Nicolson in the Commons but the motion passed overwhelminglyWishart defended Nicolson in the Commons but the motion passed overwhelmingly

He continued: “It doesn’t usually spend its day to day business ruling on something on Twitter that the Speaker might be upset about.

“John’s little video summarising what was said isn’t in the same league as Paterson or partying at number 10. It’s outrageous.

“I think the Speaker got a bit upset that he hadn’t properly apologised, but to put on all of this. It's just extraordinary that they would go to such lengths to try and bring John into line.”

Anne McLaughlin, SNP MP for Glasgow North East, added: “I now understand and John now understands that the parliamentary rules are such that you can't reveal the contents of correspondence from The Speaker.

“It's hardly the biggest issue facing parliamentarians, it will have precisely no impact on our constituents and I can't believe we spent prime parliamentary time on it.”

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Michael Russell, SNP party president, said that the probe was a “vindictive farce” in an “archaic” parliament.

He said: “It looks as if the Westminster establishment have decided that the best reaction to the normal search for justice and democracy that typifies the SNP approach is to try and crack down on SNP elected members whilst also trying to do the same to the elected SNP Scottish government.

“Such aggressive repression attempted against those who stand up for the people they represent never worked in any other such situation, where a nation was peacefully seeking independence from the British state, and it won’t work in this one. But they don’t seem to be willing to learn that lesson from history.”

Of Scotland’s six Scottish Tory MPs, three voted to refer Nicolson for investigation, David Duguid, John Lamont and David Mundell, while three did not record a vote, Scotland Secretary Alister Jack, Scottish Tory leader Douglas Ross and Andrew Bowie. 

Alba’s two MPs, Neale Hanvey and Kenny MacAskill, did not record a vote.

Labour's only Scottish MP Ian Murray voted for the motion to pass. 

Overall, 248 Tory MPs, 100 Labour, 10 LibDems, seven DUP, two independents and one Alliance MP, voted in favour of the motion.

Nicolson was contacted for comment.