WIDESPREAD online abuse was widely seen as a stain on the 2014 independence referendum, but with a second vote now looming on the horizon and Brexit tensions making the atmosphere febrile, there are fears that the worst excesses of online trolling are about to simmer to the surface once again.

In the past so-called 'cybernats' – outspoken online supporters of independence – were seen as the worst offenders, however, that was a skewed perception, which failed to put the behaviour of so-called 'cyberbrits' under the spotlight to an equal extent.

High-profile cases of abuse against prominent opponents of independence such as author JK Rowling gained much more widespread attention than threats and vilification against supporters of independence. For example, only this week the highly controversial pro-independence blogger, Stuart Campbell who runs the site Wings over Scotland, claimed Unionist trolls posted death threats against him, as part of a campaign of intimidation targeting independence supporters in the wake of the Brexit vote and in the shadow of 'indyref2'.

In a bid to set the record straight, the Sunday Herald spoke to figures from both sides of the divide.

Campbell, who has himself come under criticism for trolling and being abusive, claimed online abuse from hardline sections of the Unionist camp was the “great undocumented phenomenon of the independence debate".

Campbell told the Sunday Herald that some unionist opponents were "talking – openly, in public, under their own names – about torturing the likes of me to death".

He cited online posts about him stating "someone just put a bullet between his eyes" from an Alan Taylor, while another from a Bill McIntosh said Campbell needed to be "exterminated – slowly and painfully".

A posting from a William Neish, said, "I have just been advised of his address" and "I'll smash your head and ask questions later". He has reported the threats to the police.

Mainstream Unionist supporters condemned the threats against the blogger and called on all sides to abandon such tactics in the event of a fresh referendum.

Former Scottish Labour MSP Graeme Pearson, chief executive of the pro-UK group Scotland in Union, warned that such online threats create an "atmosphere of fear" among the electorate. Pearson, a senior police officer who served as head of the Scottish Drug Enforcement Agency, said abuse from both sides had frightened some voters into silence.

He said: "It shouldn't matter what he [Campbell] has said. There's no justification for death threats and even if there is no substance to them it creates an atmosphere of fear.

"I spoke to people on the doorstep who had views [in 2014], but some people were frightened and remained silent. I hope that we can leave that behind.

"A lot of the public comment in cyberspace was largely from anonymous people on both sides, but there's no sense in one side claiming to be less vitriolic than the other."

Scottish Liberal Democrat leader Willie Rennie, echoing Pearson's remarks, said: “A political debate immersed in poison will simply drive sensible and rational people out of politics."

Former First Minister Henry McLeish also called for end to online abuse he said could be "obsessive and often violent in tone" that he said "applies to both sides".

However, Campbell's claims of persecution may elicit less sympathy from others following his involvement in a series of high-profile, bitter online exchanges.

Campbell was previously criticised for claiming Liverpool fans were partly at fault over the deaths of the Hillsborough victims. In September 2012, a day after an independent panel found that policing failures were responsible for the disaster, Campbell wrote a controversial article that sparked a furore.

The Bath-based blogger wrote: "The police's mendacious attempts to blame the fans for being drunk, late or ticketless were red herrings. The reality is much simpler, and required no lying – the fans were to blame because they, alone, were the ones who pushed and thereby caused the crush."

Campbell also reportedly tweeted to anti-independence campaigner Andrew Skinner in 2014: ‘I’d just like you to f*** off to Ireland’.

Last night, Campbell said both sides were guilty of online abuse, but insisted that only abuse directed against Unionists was ever highlighted by the mainstream media. Apart from the Sunday Herald, few papers have tried to look at the issue of online abuse in Scotland in a fair and balanced fashion, highlighting wrong-doing on both sides.

Campbell said the Brexit vote and Donald Trump's election made "really aggressive behaviour seem more mainstream and acceptable" and led to an onslaught against independence supporters.

"Abuse from the Unionist side has always been the great undocumented phenomenon of the independence debate – it happens on both sides, of course, but only one gets reported because almost the entire media is Unionist. But I'd say it's gotten noticeably worse since Brexit, for a variety of reasons," he claimed.

"One is simply that it's emboldened a certain type of extreme British nationalist – the tone of the EU referendum campaign and the US Presidential one made really aggressive behaviour seem more mainstream and acceptable, plus once they won they didn't feel any need to rein themselves in any more.

"But also, the Brexit vote made a second indyref all but inevitable, and they're almost demented with anger about that, because they really thought they'd killed the Yes movement in 2014.

"The fact was that without Brexit there wasn't plausibly going to be any justification for another referendum for years, but now it's going to happen much sooner than anyone thought and there's a very real chance they'll lose this time, and they're outraged."

SNP MEP Alyn Smith claimed there was "a lot of nasty people online" across both sides of political divide.

He said: "Online discourse is crucial to where politics in Scotland is going, but people have to remember that what they would not have said in person they shouldn't say online.

"I mute about four people a day and have a rule that you 'don't feed the trolls'. There are a lot of nasty people online full stop. People need to be responsible for their own behaviour."