PM Boris Johnson took part in No 10 Christmas quiz last year

Prime Minister Boris Johnson took part in a Christmas quiz in No 10 last year, Downing Street has confirmed.

The Sunday Mirror published a photo of the PM at the event, which it said took place on the 15 December - when indoor household mixing was banned in London.

Downing Street admitted Mr Johnson "briefly" took part to thank staff for their work during the pandemic.

Labour's deputy leader Angela Rayner said the PM was "unfit to lead this country".

"Boris Johnson really believes it's one rule for him, another for everyone else," she said.

It comes the day after 10 Downing Street cancelled its 2021 Christmas party amid growing anger over a different gathering on 18 December last year.

After criticism from opposition parties, the media and his own MPs, the prime minister asked Cabinet Secretary Simon Case to carry out an investigation into the 18 December party earlier this week.

The inquiry will also include finding out what happened at another Downing Street gathering on 27 November last year, and another at the Department for Education on 10 December.

Allegra Stratton quit her post as a government spokesperson on Wednesday after a backlash over a video she appeared in from last December, in which she joked about a Christmas party.

The row over Christmas parties continued to escalate as the government announced new rules in England to tackle the spread of Omicron.

Mr Johnson faces a rebellion from about 60 Conservative MPs when the measures are put to a vote in the Commons next week.

Government sources suggested the introduction of Plan B measures for England will be divided into three separate votes on Tuesday, including one on Covid passes which are opposed by some Tories.

But the measures are expected to become law as Labour is backing the government.

On Saturday, a further 633 Omicron cases were reported - although the real number is estimated to be much higher. Overall, a further 54,073 daily cases were recorded across the UK.

It also said the number of deaths could range from 25,000 to 75,000 between now and April.