A police investigation into a controversial David Starkey interview will be reviewed to ensure it is “proportionate”.

Historian Dr Starkey attracted widespread criticism after he said slavery was not genocide because there are “so many damn blacks” still around in an interview with Brexit campaigner Darren Grimes

The Metropolitan Police began an investigation into a potential public order offence on September 25, but on Monday a senior officer was appointed to review the inquiry.

Police interviews with Mr Grimes and Mr Starkey have been postponed.

Mr Grimes called the investigation a waste of money and police time, and claimed it impinges on press freedom in a series of tweets.

In a statement on Tuesday, Dr Starkey defended Mr Grimes, calling the focus of the investigation into him “unfortunate and grossly unfair”.

The Metropolitan Police did not identify either of the men, but said in a statement: “On July 4, the Metropolitan Police Service was passed an allegation from Durham Police of a public order offence relating to a social media video posted on June 30.

“The matter was reviewed by officers and on July 29 a file was submitted to the Crown Prosecution Service (CPS) for early investigative advice.

“On September 25 early investigative advice was received and officers began an investigation. No arrests have been made.

“On Monday October 12 a senior officer was appointed to conduct a review of the investigation to ensure it remains proportionate and that all appropriate lines of inquiry are being considered.

“Whilst this process takes place, two scheduled interviews have been postponed. We remain in contact with the CPS.”