THE SNP’s most controversial Holyrood constituency battle has been hit by another setback after the Scottish Greens said they would also contest the seat next year.

Green MSP Alison Johnstone has confirmed she will stand again in Edinburgh Central, potentially splitting the pro-independence vote and letting the Tories hold on.

After Ms Johnstone got 4,644 votes in the seat in 2016, then Scottish Tory leader Ruth Davidson won just 610 over the SNP.

With Ms Davidson quitting Holyrood for the Lords in May, the seat has become a top SNP target.

However Ms Johnstone standing could help the Tories cling on at the expense of one of Nicola Sturgeon’s closest allies, Angus Robertson, the favourite to be SNP’s candidate.

Green MSP Andy Wightman will also stand in neighbouring Edinburgh Northern & Leith. The decision was backed at the Greens’ Edinburgh branch AGM yesterday.

No Green has ever won a Holyrood seat - all its MSPs have been elected on regional lists - and the party has long coveted a first-past-the-post win. 

Reacting to the Green candidate in Edinburgh Central, Mr Robertson warned: "Any progressive votes cast for the Greens, Labour or the Lib Dems will actually help the Tories".

Edinburgh Central has become synonymous with SNP infighting in recent months, as the candidate selection race has become mired in claims of dirty tricks and ‘dark money’.

A common thread to the complaints is that SNP HQ is tilting the playing field in favour of Mr Robetson, a former SNP deputy leader, who is an old friend of the First Minister. 

Mr Robertson lost his Moray seat at Westminster to the current Scottish Tory leader Douglas Ross in 2017, and is keen to make a comeback at Holyrood.

When the SNP started its selection process, Mr Robertson’s main rival for the candidacy was the Joanna Cherry QC, the MP for Edinburgh South West.

With Mr Robertson close to Ms Sturgeon, and Ms Cherry close to Alex Salmond, the contest became a proxy battle between the First Minister and her estranged predecessor.

In July, the SNP’s ruling body controversially changed the party’s rules in what was seen as an attempt to stitch-up the race for Mr Robertson.

The National Executive Committee decided that any sitting MP would have to give up their Westminster seat if they were selected for Holyrood, before the 2021 election.

Former SNP Westminster deputy leader Kirsty Blackman objected, saying it meant any MP interested in moving to Holyrood would have to make their staff redundant.

Ms Cherry pulled out of the race complaining it was “particularly unreasonable” to put her staff out of work in the middle of a economic crash caused by the pandemic.

Mr Robertson’s remaining rivals for the candidacy are former minister Marco Biagi, who was the Edinburgh Central MSP from 2011 to 2016, and party activist Lee-Anne Menzies.

Mr Biagi last week claimed untraceable, or ‘dark money’, was being used to promote Mr Robertson, and sid the issue had been ignored by SNP HQ.

He said rival Mr Robertson was able to spend “unlimited” sums on Facebook adverts aimed at winning over the local branch’s 1,400 members because of a lack of proper rules.

He suggested the party’s failure to impose a level-playing field and cap spending during the selection gave Mr Robertson an unfair advantage over his grassroots rivals.

Mr Robertson has spent between £1000 and £1500 on Facebook adverts for his selection campaign since July in a bid to reach the local SNP’s branches 1400 members.

Mr Biagi also complained that £1,270 of the £2,790 Mr Robertson has so far raised from a crowdfunder appeal for the internal selection race had been given anonymously. 

This includes three anonymous donations of £250 and one of £400.

Mr Robertson said he was working within the clear limits of the selection rules. 

Ms Johnstone said: “Throughout Scotland the latest polls indicate a record 10 Green MSPs being elected in May, but we aren’t taking that for granted. 

“From environmental protections to fairness for our young people, we’ve shown with six MSPs that green votes get things done. 

“With the clock ticking ever faster on climate change it’s vital to show that a Green Recovery from the coronavirus crisis is the only way forward.”

Both Ms Johnstone and and Mr Wightman are Lothians list MSPs. 

The Tories have yet to select a candidate in Edinburgh Central.

Mr Robertson said: "Edinburgh Central will be a straight fight between the SNP and the Tories.

"The way that the first-past-the-post system unfortunately means that any progressive votes cast for the Greens, Labour or the Lib Dems will actually help the Tories.

"There is a tiny Tory majority of only 610 votes, so only a vote for the SNP will be effective in defeating the Tories."