A number of social gatherings were held in Downing Street in the run-up to Christmas last year while indoor mixing was banned in London under COVID restrictions, Sky News understands.

Following reports that a large party was held in late December, it has also emerged that Number 10 staff gathered after work and drank alcohol to wind down, despite rules stating that mixing between household bubbles was banned.

On 18 December, a large party was held for more than 40 people, where staff drank, chatted and celebrated late into the night, according to a report in The Mirror newspaper.

Sky News understands this was a party to celebrate a colleague who was leaving Downing Street.

The following day the prime minister scrapped plans to allow Christmas mixing for families amid rising COVID case numbers and days later a fresh lockdown was in force.

Downing Street has insisted that no rules were broken during the period.

When pressed on the gatherings staff held throughout the period a Number 10 spokesman said: “COVID rules have been followed at all times.”