The transport secretary has denied all knowledge of the party, which The Mirror reports took place on Wednesday 16 December 2020. The new rules introduced that same day banned people from different households from mixing.

A DfT spokesperson apologised for the "inappropriate" event and its staff’s "error of judgement", while adding: "The secretary of state wasn’t involved in any gathering at the department."

The department said "fewer than a dozen staff" were involved, adding the gathering took place "in a large open-plan office".

A spokesperson for Shapps said the secretary of state had "absolutely no idea" about the event. "He was not notified or invited and would have banned such a gathering forthwith had he been made aware that it was being prepared," they said.

It is the latest in a series of reports of similar incidents during the pre-Christmas period last year spanning several departments, including Number 10, shadow transport minister Mike Kane said it was indicative of a "culture" of rule-breaking within Whitehall.