Almost 150 people tested positive for coronavirus in Denbighshire during the week of an alleged Downing Street Christmas party, figures reveal.

Prime Minister Boris Johnson has ordered an investigation into claims staff broke lockdown rules by holding a party at Number 10 last year, and told MPs he was “furious” about footage apparently showing aides joking about it.

Mr Johnson apologised for the offence caused by the leaked video but insisted he had been repeatedly assured “there was no party and that no Covid rules were broken” on December 18.

Figures from the UK coronavirus daily dashboard show 149 positive Covid-19 cases were recorded in Denbighshire between December 12 and 18 last year.

The Prime Minister’s intervention followed a week of official insistence that no party took place when London was under Tier 3 restrictions – despite reports staff drank alcohol and exchanged Secret Santa gifts.

Labour leader Sir Keir Starmer said the Prime Minister’s apology raises more questions than answers as he had been “caught red-handed”.

He added: “Millions of people now think the Prime Minister was taking them for fools, that they were lied to. They are right aren’t they?”

Mr Johnson's adviser and former press secretary Allegra Stratton emotionally resigned after leaked footage showed her laughing as she appeared to rehearse answers to questions over a lockdown-busting Christmas party.

The video from No 10’s £2.6 million press briefing room, which is reported to be from December 22 last year, refers to a party on “Friday” – the same day The Daily Mirror reported there was a staff party where games were played, food and drinks were served, and revelries went on past midnight.

At this time, coronavirus restrictions were being reintroduced across many parts of the UK ahead of Christmas amid fears over the emergence of the 'Delta' variant.

Mr Johnson agreed that any evidence uncovered about parties in Downing Street would be handed over to police.

Statistics published by the National Police Chiefs' Council reveal a total of 43 fixed penalty notices were issued by North Wales Police for breaches of Covid-19-related laws between November 17 and December 20 last year.