AN independent watchdog is to investigate Gloucestershire Police over the collapse of a trial of four men accused of the gang rape of a woman at a leading university.

James Martin, of Hook Norton Road, Swerford, aged 20, and Thady Duff, Leo Mahon and Patrick Foster, all 22, were accused of raping the woman at a summer ball at the Royal Agricultural University in Cirencester, Gloucestershire, in May 2014.

She claimed she had been subjected to violence, including strangulation, and some of it had been filmed and posted on Snapchat.

The trial had been due to begin at Gloucester Crown Court in March but, following delays due to the late disclosure of evidence and a review of the case, the prosecution offered no evidence and the four defendants were cleared.

Last week during a hearing on defence costs, Judge Jamie Tabor QC, the Recorder of Gloucester, criticised Detective Constable Ben Lewis, the lead officer.

The judge said Det Con Lewis had got too close to the complainant and did not understand his job properly, which led to “stark and very serious omissions” by the officer in failing to disclose “game-changing” evidence.

The Independent Police Complaints Commission has decided an independent investigation is “appropriate”.

It said in a statement: “Issues have been raised concerning the police investigation and the disclosure of evidence in preparation for the trial.

“The matter was referred to the IPCC and we have decided an independent investigation is appropriate.

“The IPCC will carefully examine the actions of the officers involved during both the investigation and the pre-trial process.”

After the collapse of the trial, the defendants’ barristers criticised Det Con Lewis for “cherry-picking” supportive evidence and “airbrushing out of the picture” anything that could have helped the men.

This included text messages sent by the complainant in the hours after the alleged incident and a conversation with a friend about what would happen if the video became common knowledge.

The mobile telephone evidence was only recovered when experts instructed by the defence carried out a full examination of the device.

It also emerged as the trial was due to begin that police had failed to disclose that the complainant was a witness to an alleged rape on an Army base in October 2014 and that there were inconsistencies in her evidence. The alleged rapist was a soldier but he was later cleared.

Mr Duff, is of Stubbs Hill Farm, Swindon; Mr Mahon, of Lawrence Road, Cirencester and Mr Foster, of Maldon Road, Kelvedon, Colchester.