The Green Party of England and Wales is reviewing its social media operation which has been central to its surge in popularity over the past year, sources have told the BBC.

They insist it is not connected to the backlash to Zack Polanski this week after he re-posted a photo of a man wearing a t-shirt with an image of a guillotine and the slogan “we’re only making plans for Nigel” – seen as being a reference to Nigel Farage.

But that incident has raised questions about whether it is sustainable for the Green Party leader to manage his own social media channels, with one party figure calling it an “avoidable mistake” and that Polanski “should have said sorry” for it.

In an interview with BBC Newsnight, Polanski repeatedly refused to apologise for “an inadvertent mistake” but acknowledged he needed to “be better on social media”.

“I just didn’t look carefully enough and I accepted it, as soon as I was aware of what happened I unaccepted it and took it down,” he said.

Like other high profile figures on social media, Polanski receives a lot of material from other users seeking re-posts. But unlike most political leaders in the UK, he still manages his own accounts, rather than handing control to party staffers.

This may allow him to appear spontaneous and authentic – both valuable commodities on social media – but it comes with risks.

The current row began after Polanski shared a single post on Instagram that contained a carousel of 20 pictures.

The re-post was shared to Polanski’s 713,000 followers, because he accepted a request to tag him as a collaborator, which on the platform makes him a “co-author,” placing it on his page and into his followers’ feeds.

Polanski said he had not noticed the offending image among the others on the post.

According to him, he had accepted collaborator tags for eight other posts from the same event in Bristol alone.

Reform UK leader Farage claimed the t-shirt amounted to incitement to murder and his party reported it to the police.

Neither the Metropolitan Police nor Avon and Somerset Police say the incident meets the threshold for further action.

But the political row has continued with Reform UK MP Robert Jenrick calling Polanski a “nasty piece of work”, at a news conference earlier on Thursday.

Inside the Green Party, there has been some criticism of Polanski’s behaviour online.

He has attracted positive and negative attention for the rate at which he posts, comments, likes and replies across multiple platforms including X, Bluesky, Facebook and Instagram.

And this is not the first time a quick reaction has attracted controversy; last month he had to apologise to police after posting about their response to the Golders Green attack.

One senior party source said it was clear that due diligence had not been done on Polanski’s social media output, and that moving forwards he needs “tight controls” to stay credible, while keeping a similar tone of engagement with his followers.

They pointed out that the speed and number of Polanski’s interactions came with a “small upside” but a “colossal downside”, and with the latest incident he had “shot himself in the foot at precisely the wrong time”.

It comes as recent polling suggests the Green Party has lost ground to Labour, following Andy Burnham’s election as Labour leader, and down from a peak earlier this year.

They added their concerns about a wider problem with the party’s vetting on social media and of candidates, including around antisemitic posts in recent months.

Several candidates in recent elections have stood down over their social media activity, with two candidates arrested during May’s local elections, and another suspended after being elected.

But Green Party peer and former deputy mayor of London Baroness Jones said the criticism of Polanski’s Instagram re-post seemed to be “mainly from our opponents, not internal discussions”.

She said that her party leader had “made a mistake”, adding “we’ve all done it and got flak.”

But she added: “His online presence is what makes him relatable”.

Along with relatability, comes popularity: Polanski is the second-most followed UK leader on Instagram after Nigel Farage. The Greens surpassed other parties to become the most popular on the platform this year.

It is also seen as where a good portion of their voters spend time, as they are the most popular party among the under-30s, according to pollsters YouGov.

A separate party source confirmed there was a review going on internally into the party’s social media operation, but would not be drawn on whether that meant changing who had oversight of Polanski’s posts.

“We are looking at our processes and systems in this area,” they said.

“Obviously Zack is really active on social media. It is how we have grown our reach and our membership.”

Until around a year ago the party’s entire social media team consisted of one full-time employee.

That has now gone up to three or four and may increase further following the review.

“We have expanded hugely as a party and we are looking at how we work,” the source said.

“As part of that we are looking at what we might do to support and beef up our social media team.”

They said the coverage of the Instagram re-post row had been “deeply irritating” but added that the review was not directly linked to that incident.

But it remains to be seen how much longer Polanski can retain control of his accounts before handing over the passwords to party staffers.

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