The Queen will not attend the Royal Variety performance tonight due to ongoing symptoms from her recent chest infection, a Buckingham Palace spokesperson said.
Camilla had been due to join the King at the event on Friday night which is taking place at London’s Royal Albert Hall and will feature performances from stars including Sir Elton John and Sophie Ellis-Bextor.
The Queen has appeared at several events after falling ill with the infection earlier this month but doctors have advised her that she should prioritise rest.
A Buckingham Palace spokesperson said: “Following a recent chest infection, the Queen continues to experience some lingering post-viral symptoms, as a result of which doctors have advised that, after a busy week of engagements, Her Majesty should prioritise sufficient rest.
“With great regret, she has therefore withdrawn from attendance at tonight’s Royal Variety Performance. His Majesty will attend as planned.”
A Royal source said the Queen was “naturally disappointed to miss the evening’s entertainments, and sends her sincere apologies to all those involved, but is a great believer that ‘the show must go on’.
“She hopes to be back to full strength and regular public duties very soon.”
It is understood Camilla will remain in London on Friday and will then travel Sandringham for the following week as planned.
It follows reports that the Queen is said to be "heartbroken" after the death of her dog Beth.
Camilla said goodbye to her Jack Russell terrier at the weekend when the dog was put down following a diagnosis of an untreatable tumour.
A message from Buckingham Palace posted on social media read: "A sad farewell to Beth, the Queen's muchloved companion from Battersea Dogs and Cats Home who brought such joy, whether on walkies, helping on official duties, or curled up by the fire."
