Liz Truss was informed that the Queen was gravely ill before she entered Parliament to deliver a major statement on energy bills.
It had been believed that the new Prime Minister first became aware of the Queen's condition when she was handed a note in the Commons by Nadhim Zahawi, the Chancellor of the Duchy of Lancaster, shortly after 12pm.
Labour leader Keir Starmer and his deputy Angela Rayner, and Commons Speaker Sir Lindsay Hoyle were also briefed, setting off a flurry of speculation before Buckingham Palace released a statement saying doctors were concerned for the Queen's health.
