Ms Stratton is understood to have taken part in several sessions to prepare her for “White House-style” televised briefings, with Government special advisers posing as journalists.

The plan for on-screen press conferences was eventually abandoned, after Mr Johnson was advised that she had not performed well in the practice sessions.

Mr Zahawi said yesterday the leaked quiz photo did not show evidence of a breach of the rules and called on media outlets not to exaggerate the scale of the December 18 “party”.

Asked about the virtual quiz yesterday, Mr Zahawi said: “What do we see in that picture?

“We see a Prime Minister on a virtual quiz night for 10 to 15 minutes to thank his staff, who by the way, had no choice but to come in every single day.

“Sitting in his office are the two people who are closest working with him, no alcohol on the table, not drinking, on a Zoom call or a Teams call, a virtual call respecting the lockdown rules.

“Many people would have had similar Zoom quiz nights around the country.”

He added that there was not “a rule against recognising Christmas with tinsel or a hat”, as the staff pictured on either side of Mr Johnson appeared to be doing.

An official inquiry into the events by Simon Case, the Cabinet Secretary, has scope to include any parties attended by government officials, and will report back to the Prime Minister, who has said disciplinary action will be taken against people found to have broken the rules.