The leaked memo, obtained by ITV, said: “Consistent with its indication that it will not publish the identities of anyone issued a FPN, we would not expect the Met to publish photographs. The Liaison Unit has asked the Met to confirm this.”

The Telegraph understands that officers have not yet replied to the message to confirm that they will not release the photographs, but it would be unusual for a police force to release evidence relating to a crime punishable with an FPN.

The Met has previously said it will not identify civil servants who are reprimanded, but Number 10 has said it will declare the fixed penalty notice if Boris Johnson is fined.

The Prime Minister and other Downing Street staff have received a Met Police questionnaire about the 12 events under investigation. Mr Johnson has also hired a lawyer.

The Telegraph understands it is unlikely that the Gray report, which is separate to the police investigation, will contain the images her team obtained while investigating the parties.

Officials familiar with the investigation believe Ms Gray will explain what she learned from the images but will not describe them at length. Although some images of a Downing Street Zoom quiz have been published in the press, any more damaging images of the parties themselves have been kept secret.

If they are not leaked to the media, it is likely that they will never be seen by the public.

A source said it would be “unprecedented” for the Government to voluntarily publish photographic evidence showing the wrongdoing of its own staff.

The Cabinet Office declined to comment.