The Metropolitan police was slow to learn lessons from its disastrous investigation into bogus claims of a VIP paedophile ring in Westminster, an official report has found.

The report by Her Majesty’s Inspectorate of Constabulary (HMIC) also found that problems continue in key areas, such as following the rules to obtain search warrants.

The home secretary, Priti Patel, ordered the report in October 2019 to examine whether the Met had learned lessons from Operation Midland.

That investigation saw detectives fall for the lies of Carl Beech, a fantasist who claimed he was the victim of a VIP child sex abuse and murder ring.

Properties belonging to prominent figures including D-Day hero Lord Bramall, former home secretary Leon Brittan and former Tory MP Harvey Proctor were raided.

Carl Beech was later convicted of lying and fraud, and jailed for 18 years. When Operation Midland collapsed the Met commissioned retired judge Sir Richard Henriques to investigate, and a heavily redacted version of his report and recommendations was released in November 2016.

The HMIC report examined the Met’s response to that report and found it “underwhelming”, report author Matt Parr told the Guardian.

The report found that a group of senior officers did not prioritise putting mistakes right: “We were left with the impression that the group saw no particular role for itself in overseeing implementation of the recommendations or ensuring that the MPS (Metropolitan police service) had learned the wider lessons. The group’s discussion was heavily weighted towards restricting access to the report, rather than learning the lessons from it.”

The Met wrongly believed the Home Office would take responsibility since the lessons also applied to other forces. It also thought that looming discipline inquiries into officers, and the criminal trial of Beech, precluded it from doing more.

Parr said he accepts the Met was under pressure from rising crime but said: “The concern is an organisation with the resources of the Met could and should have done more.”

Proctor, who has been a vocal critic of the force, said: “They tried to cover up the failings of the Met rather than make sure those failings did not occur again.

“They were trying their best to stop the full Henriques report coming out.”

Proctor said the Met only acted in October 2019 – when the commissioner ordered a new initiative – because they knew they had the support of the home secretary and HMIC coming in to investigate them.

Asked if the Met had only upped its game after pressure from the home sectary and after fuller extracts of Henrique’s report were published in October 2019, Parr said: “You might conclude that.”

HMIC’s inquiry also found continuing problems with police handling of search warrants.

This is a key issue because Henriques found that warrants to raid home of suspects in Operation Midland were obtained from a court on the basis of incorrect information. HMIC said it quizzed officers and was concerned that “just under half (48%) of the police officers who responded to our survey told us they had never had any training in how to apply for a search warrant. Our findings call into question the levels of understanding among some applicants, and the robustness of the authorisation process by some inspectors.”

HMIC said that unique circumstances contributed to the Operation Midland disaster and that they were unlikely to reoccur.

The Met commissioner, Cressida Dick, owes her job to the home secretary and to the mayor of London, who continues to have full confidence in her.

Dick said: “Operation Midland had a terrible impact on those who were falsely accused by Carl Beech. The previous commissioner and I have apologised to them and I repeat that apology again today.

“The MPS took Sir Richard’s report extremely seriously and quickly recognised that many of the recommendations would affect policing nationwide.

“However, the inspectorate believe more work should have been done between the initial response and our current renewed focus following the conviction of Carl Beech and the conclusion of the Independent Office for Police Conduct investigation.

“In October 2019 I set up Operation Larimar [to implement Henriques’ recommendations], led by a senior officer reporting directly to me. This structure is ensuring we make ongoing progress.”

In his report, Henriques said a policy of believing the victim led astray detectives in Operation Midland. The policy has now been revised amid huge debate in policing.

David Tucker of the College of Policing, which sets standards for officers, said: “It is vital that decisions on crime recording are taken with a broad view about the impact changes might have. We know that the reporting rates for sexual offences, domestic abuse and other … crimes have increased.

“All those involved in the process of recording and investigating crimes need to be clear that a victim is believed for the purposes of recording a crime unless there is evidence that the incident didn’t happen. Thereafter, an impartial investigation should follow.”