A High Court judge “fell into error” when sentencing a former BBC local radio presenter to five years and 26 weeks in prison for stalking broadcasters including Jeremy Vine, the Solicitor General has said.

Alex Belfield, 42, who “weaponised the internet”, was found guilty at Nottingham Crown Court of waging a relentless campaign, with TV star Mr Vine subjected to an “avalanche of hatred”.

Mr Vine labelled Belfield “the Jimmy Savile of trolling” during a trial, which heard he repeatedly posted or sent abusive messages, videos and emails.

In a letter to the Victims’ Commissioner for London last month, Solicitor General Michael Tomlinson said he agreed the judge made an error, adding: “The sentence may be unduly lenient.”

Mr Tomlinson said the case was re-listed before the sentencing judge, Mr Justice Saini, where he “agreed that there had been an error in his approach to sentencing” but opted not to alter the sentence.

In the judge’s ruling where he accepted the error, he said he was “misinformed” by the prosecution about the maximum sentence available to him on one of the counts Belfield was convicted of.

Mr Justice Saini said it was “regrettable that this was not drawn to my attention earlier”, adding: “Mr (John) McGuiness KC, leading counsel for the Crown, has provided a frank and gracious apology to the court, which I accept. This was an oversight.”

The judge said he did not alter the sentence given to Belfield because it would have only been “modestly” higher and the “overall sentence fairly reflects the totality and seriousness of all the offending.”

London’s Victims’ Commissioner, Claire Waxman, wrote back to Mr Tomlinson to express her “deep disappointment” the case could not be referred under the Unduly Lenient Sentence (ULS) scheme due to a 28-day time limit on referrals.

She said Belfield’s case proved “injustice within the ULS scheme continues” and the “current system is simply not fit for purpose”.

Jurors accepted Belfield caused serious alarm or distress to two victims and found him guilty of “simple” stalking in relation to Channel 5 and BBC Radio 2 presenter Mr Vine and theatre blogger Philip Dehany.

BBC Radio Northampton presenter Bernie Keith was left suicidal by a “tsunami of hate”, the trial was also told.

In his letter to Ms Waxman, Mr Tomlinson said the judge’s error was in relation to the sentencing conclusion over Belfield’s nine-year campaign against Mr Keith.

The Solicitor General concluded by saying: “The matter was listed before the sentencing judge on October 21 and, although he agreed that there had been an error in his approach to sentencing, he declined to interfere with the sentence.

“I understand that the offender is seeking to appeal the sentence and, if he does so, my office will request that the CPS (Crown Prosecution Service) draws the sentencing error to the court’s attention.”

Mr Vine gave evidence against Belfield, of Mapperley, Nottingham, telling jurors: “This is not a regular troll here. This is the Jimmy Savile of trolling.”

Likening watching Belfield’s videos to swimming in sewage, Mr Vine said of the defendant’s conduct: “It felt like I had a fish hook in my face and my flesh was being torn, and the only way to avoid further pain was to stay completely still.”

Jurors convicted Belfield of four charges committed between 2012 and 2021.

In his sentencing remarks, Mr Justice Saini said Belfield, who has 361,000 followers on his YouTube channel, The Voice Of Reason, and 43,000 on Twitter, directed his attacks via social media “in highly negative and often abusive terms”.

As well as jailing Belfield, Mr Justice Saini issued indefinite restraining orders banning the DJ from contacting his victims.

Similar orders in favour of four other individuals – the BBC’s former head of the north Rozina Breen, former BBC Radio Leeds presenters Liz Green and Stephanie Hirst and BBC executive Helen Thomas – were also made.