A leading human rights barrister has accused the police watchdog of ‘abject failure’ and a ‘dereliction of duty’ in its investigation into Scotland Yard’s disastrous VIP child abuse inquiry.

Geoffrey Robertson, QC, criticised the competence of the Independent Office for Police Conduct (IOPC) in a showdown with its director general Michael Lockwood.

Mr Robertson told Mr Lockwood that the Metropolitan Police’s Operation Midland investigation had been conducted ‘incompetently, negligently and with what might be described as institutional stupidity’.

Leading human rights barrister Geoffrey Robertson has criticised the competence of the Independent Office for Police Conduct in a showdown with its director general Michael Lockwood (pictured). He also accused them of 'abject failure' and a 'dereliction of duty'

Mr Robertson said that the Metropolitan Police's Operation Midland had been conducted 'incompetently, negligently and with what might be described as institutional stupidity'. It comes over the investigation into allegations made by VIP abuse fantasist Carl Beech

‘These are failures for which the IOPC should hold the police accountable, as well as for breaches of discipline,’ he added.

Mr Robertson is head of the legal team representing former Tory MP Harvey Proctor, who was falsely accused of being a serial child killer by VIP abuse fantasist ‘Nick’, real name Carl Beech.

Scotland Yard spent 16 months and £2.5million investigating the allegations before officers realised Beech had told a pack of lies.

Beech was later revealed to be a paedophile himself and was jailed for 18 years in July for fraud and perverting the course of justice. Despite retired High Court judge Sir Richard Henriques identifying 43 major blunders in Operation Midland in an official report three years ago, of which only a heavily redacted version was published, the IOPC has cleared five officers of misconduct.

Two – Deputy Assistant Commissioner Steve Rodhouse and Detective Superintendent Kenny McDonald, who described Beech’s allegations as ‘credible and true’ at the outset – were exonerated without even being interviewed.

Yesterday Mr Robertson condemned the ‘whitewash’ by the watchdog. His joint statement with Mr Proctor and respected media lawyer Mark Stephens will put pressure on Home Secretary Priti Patel to order a fully independent criminal investigation into the conduct of police.

Geoffrey Robertson QC (pictured) also said that the police watchdog's investigation had been conducted ‘incompetently, negligently and with what might be described as institutional stupidity’

It said the IOPC had failed in its duty to protect the public from police incompetence, gross negligence and institutional stupidity. By announcing that the Met had no case to answer, it had whitewashed Operation Midland.

Mr Justice Henriques’ full report ‘is explosive; it reveals in detail the staggering incompetence of Operation Midland’, it said. Mr Robertson criticised the IOPC for its ‘abject failure’ to condemn the senior policemen who declared Beech ‘credible and true’ when ‘they knew his allegations were not only incredible and inconsistent but there was not a shred of evidence to confirm them...

‘[It] amounted to a public declaration that distinguished men were guilty of the vilest crimes of murder and rape of children.’

Examination of the Met’s search warrant application to raid Mr Proctor’s home showed that police had withheld information from a district judge which would almost certainly have caused him to reject their request, it said. The decision to publish a fuller version of the Henriques report was announced last month after Sir Richard told the Daily Mail that police searches on the homes of retired armed forces chief Lord Bramall, ex Home Secretary Leon Brittan and Mr Proctor broke the law.

On Saturday the Mail revealed that Scotland Yard chiefs are consulting officers involved in Operation Midland about what should be cut from it.

The IOPC said: ‘Our final investigation report will be published later this month, having drawn our own, independent conclusions. We investigated the conduct of three MPS officers – a detective sergeant, a detective inspector and a detective chief inspector – who were involved in applying for warrants in relation to properties connected to Lord Bramall, the late Lord Brittan and Harvey Proctor.

‘While the investigation found that none of the officers deliberately withheld evidence from the applications with the intention of misleading the district judge and would have no case to answer for misconduct, our investigation has identified clear shortcomings.

‘We appreciate Mr Proctor has experienced considerable distress and anxiety as a result of the allegations made about him, which were ultimately found to be false. It is important that we identify learning from the experiences of victims and do all we can to ensure the mistakes made are never repeated.’