Gay former London mayoral aide, barrister and city alderman Simon Walsh has been found not guilty of five counts of possessing extreme pornography and one count of possessing an indecent image.

The jury at Kingston Crown Court returned the verdict today in what was believed to have been the first trial live-tweeted by a solicitor, under the hashtag #porntrial.

Myles Jackman of Hodge Jones & Allen tweeted this afternoon that a ‘not guilty’ verdict had been returned by all jury members at Mr Walsh’s trial.

The case was brought after images of fisting and other sexual activities were found by police in a personal email account Mr Walsh used regarding his sex life.

Mr Walsh, 50, was standing trial under section 63 of the Criminal Justice and Immigration Act 2008 at Kingston Crown Court.

The recently-introduced law makes it an offence to possess “an extreme pornographic image”, which is “grossly offensive, disgusting or otherwise of an obscene character” and depicts an action that is either life-threatening, or likely to result in “serious injury” to a person’s anus, breasts or genitalia.

The prosecution was unable to prove the acts featured in the pictures found in Mr Walsh’s email account, which included images of fisting and insertion of ‘urethral sounds’, were in his possession and met the above criteria to be considered ‘extreme’.

The sixth count alleged that one image found in the email account was of an under-age boy, a charge denied by Mr Walsh and not successfully proven in court.

Journalist, lawyer and legal commentator David Allen Green tweeted today: “#PornTrial was a shameful and intrusive prosecution. The CPS disgraced itself bringing it.

“What was especially nasty about #porntrial was the baseless CPS allegation of child porn. Utter smear against a good man.”

He added: “Fifty Shades of Grey is, it seems, the best selling book ever in Britain, whilst the CPS prosecute #porntrial. Odd society, ours.”

In his career as a barrister, Mr Walsh had been involved in the prosecution of police officers accused of disciplinary offences, a point which has been raised by many on Twitter.

Science writer Dr Ben Goldacre tweeted: “With every #porntrial all I can think is: nobody cares. What has made you – the police, CPS, a judge – so interested in other ppls bottoms?”

On Monday, a CPS barrister, whose identity was unclear, was reported to have asked a witness: “People who attend sexual health clinics engage in more risky practices, do they not?”

The witness, Dr Clarissa Smith, Reader in Sexualities and Culture, University of Sunderland, replied: “No, people who attend sexual health clinics take their sexual health seriously.”

Update at 1546

After the trial today, Myles Jackman said: “This intrusive prosecution into the private sexual fantasies of consenting adults was brought with the DPP’s express consent. It took a jury to defend sexual freedoms by repelling the voyeur State from intruding on the privacy of an individual’s bedroom.”

Alex Dymock, a researcher for Backlash, an umbrella campaign providing academic campaigning and legal resources in the defence of freedom of sexual expression, who was also tweeting from the courtroom, said: “The CPS seems to be fixated with prosecuting representations of relatively common, private sexual acts between adult men. If lack of consent cannot be proven, are there really sufficient grounds to intervene?”