The police watchdog is conducting a review to “determine whether appropriate steps were taken” before the resignation of its boss who became the subject of a criminal investigation.

Independent Office for Police Conduct (IOPC) director general Michael Lockwood stepped down from the role last week as he was the subject of a police probe into a historic allegation.

It is understood that Mr Lockwood privately informed a Home Office official about the allegation on November 4, and that chiefs within the body were first told about it in October.

Home Secretary Suella Braverman said last Saturday that she was forced to take “immediate action” after being made aware of the police investigation.

The IOPC told the PA news agency: “We will be conducting a review to determine whether appropriate steps were taken at appropriate times.”

A spokesperson said: “In mid-October, Mr Lockwood approached the IOPC’s general counsel, David Emery, to say an allegation had been made against him and sought his recommendation on personal legal representation.

“He was provided with that recommendation and was given a copy of our conflict of interest policy by Mr Emery.

“In early November, Mr Lockwood separately advised his then deputy, Tom Whiting, and Mr Emery that he had been contacted and interviewed by the police and gave brief details of the allegation made against him.

“Mr Whiting advised that under our conflict of interest policy and our code of conduct that he must disclose this information to the Home Office as the director general is directly accountable to the Home Secretary. Mr Emery gave identical advice.

“Mr Whiting was told that the disclosure was made to the Home Office at a pre-scheduled meeting two days later, on November 4, and that Mr Lockwood was advised to continue in his role as normal.

“On Friday December 2, we understand that Mr Lockwood had discussions with the Home Office and he then informed all staff that he was resigning with immediate effect, citing personal reasons.”

The Home Office found out last week that a file was being prepared for submission to the Crown Prosecution Service, before Ms Braverman took action.

The Home Secretary said: “I have accepted Michael Lockwood’s resignation as director general of the Independent Office for Police Conduct.

“I took immediate action upon being made aware that Mr Lockwood was the subject of a police investigation into an historic allegation, and instructed my officials to ask him to resign or face immediate suspension from his role.”

The IOPC spokesman added “it would not be appropriate” to comment on an ongoing criminal investigation.

Shadow home secretary Yvette Cooper on Saturday wrote to Ms Braverman about the matter, telling her it “raises direct and serious questions about your failure as Home Secretary to ensure that the Home Office and the IOPC are taking standards seriously enough”.

The Labour MP, who submitted a list of questions to the Home Secretary, wrote: “At a time when trust and confidence in policing has been severely impacted by high-profile cases of serious police misconduct, the work of the police watchdog is more important than ever.

“As Home Secretary you have a vital role to play in showing leadership when it comes to wrongdoing by those in positions of power and if you fail in that vital leadership role you badly let down the public, the police and victims of crime.”

Mr Lockwood was the first director general appointed to lead the IOPC when it replaced the Independent Police Complaints Commission in 2018.

He was previously chief executive of the London Borough of Harrow in north-west London.

After the 2017 Grenfell Tower fire, he was asked by a Government taskforce to lead recovery and remediation work and liaise with bereaved families, survivors and the wider community.

The IOPC said on Monday that Mr Whiting had been appointed as interim director general.