Prime minister Liz Truss and deputy Labour leader Angela Rayner were handed notes in the Commons earlier this afternoon to inform them of the Queen’s health.
The pair learned during a debate on the energy crisis that the monarch is currently under medical supervision at Balmoral.
While Nadhim Zahawi, the recently-appointed Chancellor of the Duchy of Lancaster, came into the chamber to brief Ms Truss, it fell to Ms Rayner to tell Labour leader Keir Starmer about the development.
Commons Speaker Sir Lindsay Hoyle was also passed a piece of paper to let him know the news.
Labour politician Chris Bryant was quick to realise that something was amiss in parliament. “Something odd is going on in the Commons. Zahawi briefing PM urgently,” he tweeted.
Around 20 minutes later, Buckingham Palace told the public that “the Queen’s doctors are concerned for Her Majesty’s health”, adding that she is currently under medical supervision.
“The Queen remains comfortable and at Balmoral,” the Palace said.
After the announcement was made, Sir Lindsay interrupted proceedings to extend his and his peers’ well wishes to the Queen and her family.
“I know I speak on behalf of the entire House when I say that we send our best wishes to Her Majesty the Queen and that she and the royal family are in our thoughts and prayers at this moment,” he said.
“If there is anything else, we will update the House accordingly.”
By this time, Ms Truss and Mr Starmer had already left the chamber. They both were quick to release statements expressing their concerns for the monarch.
“The whole country will be deeply concerned by the news from Buckingham Palace this lunchtime,” the prime minister wrote.
“My thoughts - and the thoughts of people across our United Kingdom - are with Her Majesty The Queen and her family at this time.”
Similarly, Mr Starmer said he was “deeply worried” by the news from Buckingham Palace. “I join everyone across the United Kingdom in hoping for her recovery,” he added.
Reflecting on the mood in the Commons, Rhondda MP Mr Bryant said: “The Commons feels chilly and sombre, as if the blood has been drained from its cheeks. We wish Her Majesty and her family well.”
The Prince of Wales and the Duchess of Cornwall have travelled to Balmoral amid concerns for the 96-year-old Queen’s health.
Other members of the royal family, including Prince William and Prince Andrew, landed in nearby Aberdeen airport on Thursday afternoon en route to the Queen’s Scottish residence.
The Duke of Sussex is also heading to Scotland to be with the rest of the royal family.