Three senior Metropolitan Police officers have been cleared over their handling of allegations at the centre of an investigation into claims of a VIP paedophile ring.
The controversial investigation saw raids on the homes of D-Day veteran Lord Bramall; late former home secretary Lord Brittan and ex-Tory MP Harvey Proctor after "Nick" made a series of claims including three murders.
The Independent Police Complaints Commission (IPCC) found that Operation Midland, which looked into claims by complainant "Nick", was "extensive and carried out diligently" by a deputy assistant commissioner, a detective superintendent and a detective chief inspector.
There was no evidence to indicate "bad faith, malice or dishonesty" by the officers, the watchdog said.
However, the detective chief inspector and two junior detectives will be investigated over allegations they may have mislead a district judge in order to obtain search warrants during the 16-month probe.
Carl Gumsley, IPCC Commissioner, said: "The allegation that incomplete information may have been provided to a district judge when applying for search warrants is serious and the IPCC will thoroughly investigate this matter.
"However, a thorough assessment into the other matters that were referred to the IPCC has been carried out.
"After considering the information resulting from that assessment, I am of the opinion that there is no indication that these matters would amount to behaviour which would justify disciplinary proceedings."
Scotland Yard had also referred the conduct of the deputy assistant commissioner relating to allegations that an investigation into Lord Brittanwas extended without good reason.
The watchdog's findings come after an independent review into the investigation found Scotland Yard made "numerous errors" in the inquiry which closed without a single arrest in 2016.
Mr Gumsley continued: "It is also important to acknowledge the climate in which Operation Midland and the investigation into Lord Brittan were being undertaken.
"At this time there was much concern that cover-ups by the 'establishment' had taken place and there was widespread intense scrutiny on both investigations."
Retired High Court judge Sir Richard Henriques, who carried out the independent review in 2016, said the sole alleged victim of the £2.5 million Operation Midland had been too readily believed.
Fiona Taylor, assistant commissioner at Scotland Yard, said the force was "not afraid to learn lessons" following Sir Richard's review and had referred officers so an independent assessment of their conduct could be made.
"Whilst the Met is clear we did not get everything right, the IPCC has found no evidence to indicate bad faith, malice or dishonesty on the part of the officers as they investigated the allegations made by 'Nick'.
"The IPCC also state that the information available to them indicates the investigation was extensive and carried out diligently.
"This work was carried out against a backdrop of intense scrutiny and allegations that in the past the Met had covered up sensitive allegations about prominent people."
Mr Proctor described the IPCC statement as a "cover up" and said he did not believe the timing of its release - on the day of the Budget - was "coincidental".
"It is my view that no police officer will ever be held responsible for the bungled and disastrous Operation Midland that has ruined my life and left me destitute," he said in a statement.
The former MP said Scotland Yard and the IPCC would pay a "heavy price for its refusal to investigate the Metropolitan Police for its disastrous shortcomings" in Operation Midland.
"The IPCC expect me to accept that my reputation and life and that of others is destroyed because of the climate in which Operation Midland was undertaken - I cannot," he said.
"This is no just excuse and adds insult to injury. The context in which Operation Midland was conducted was not just."