Sir Keir Starmer has been forced into self-isolation after one of his children tested positive for coronavirus this lunchtime.
The news comes two hours after the Labour leader attended the Commons to participate in PMQs – which Prime Minister Boris Johnson contributed to virtually from his own period of self-isolation at Chequers.
It is believed Mr Starmer discovered the test result after his appearance at PMQs and had tested negative prior on Wednesday morning.
Labour leader Sir Keir Starmer attended PMQs in the House of Commons on Wednesday lunchtime
He will now begin the quarantine process alongside his family.
A spokesperson for the Labour leader said: “One of Keir’s children tested positive for COVID this lunchtime.
“In line with the rules, Keir and his family will now be self-isolating.
“Keir was already doing daily tests and tested negative this morning. He will continue to take daily tests.”
The Labour Party has confirmed this is the fourth time their leader has had to isolate since the pandemic began.
The result will force him to alter plans to launch his “safer communities” campaign on Thursday.
Boris Johnson appeared at PMQs virtually from his own period of self-isolation at Chequers
It means the prime minister, the leader of the opposition, the chancellor and the health secretary are now all in isolation as infection rates continue to increase across the country.
Health Secretary Sajid Javid tested positive with a PCR test on Saturday evening.
Both Prime Minister Boris Johnson and Chancellor Rishi Sunak were deemed close contacts of the health secretary, having attended a meeting with him in the days before.
After it was revealed that the PM and chancellor had been identified as close contacts of Mr Javid, the government announced that the pair would take part in a pilot scheme which sees isolation replaced by daily testing.
But there was a swift U-turn following a backlash, with Mr Johnson and Mr Sunak now isolating.
Sajid Javid’s positive COVID lateral flow test was confirmed by a positive PCR result on Saturday evening
And as of Wednesday lunchtime, Mr Starmer becomes the latest politician to be forced to stay at home.
Last week, data showed over half a million people were ‘pinged’ by the coronavirus tracing app which has led to some calls for the mechanism to be fine tuned.
The government has said the app will not be altered, but on Tuesday announced that some “crucial” workers will be exempt from self-isolation for work purposes so long as they test negative each day.
Reacting to the announcement on Sky News, Labour MP and Mr Starmer’s former parliamentary private secretary Carolyn Harris said: “All is fine, Keir is doing the right thing.”
On Tuesday, the UK recorded 46,558 new COVID-19 cases and 96 more coronavirus-related deaths in the 24-hour period prior, according to government data.
It is the highest number of fatalities since 24 March when 98 were reported.