The Duke of Edinburgh is expected to stay in hospital for two weeks after undergoing an exploratory operation on his abdomen on Friday.
Philip, who is 92 on Monday, was admitted to the London Clinic on Thursday following a garden party at Buckingham Palace.
He was due to accompany the Queen on her official opening of the BBC’s new £1bn home at Broadcasting House in central London on Friday.
During her visit, the Queen spoke briefly on BBC Radio 4’s Today programme, recalling her first visit to the BBC with her father before World War II.
“It is a great pleasure to visit the BBC today and to see it in its new home,” Her Majesty said on live radio. She added that her last visit had been in 1953 with the Duke of Edinburgh.
A palace spokeswoman said the duke’s operation, which will be carried out under general anaesthetic, was a planned admission following investigations carried out over the past week, and emphasised that the duke “is in very good health”.
The duke pulled out of an official engagement at the palace on Monday after temporarily losing his voice, the salace said – an illness not thought to be connected with today’s operation.
The palace said in a statement last night that the duke was expected to stay in hospital for up to two weeks. “Further updates will be issued when appropriate,” the statement added.
Prime Minister David Cameron sent Philip his good wishes, writing on Twitter: “My best wishes to the Duke of Edinburgh who is in hospital tonight. I hope he has a swift recovery.”
The Queen and the duke had appeared together on the steps of Buckingham Palace at 4pm yesterday, when the national anthem was played to mark the start of the garden party.
Despite strong sun and temperatures of around 22C, Philip appeared relaxed and happily chatted to guests as he walked around the garden, giving no indication of his imminent admission to hospital.
Lord-Lieutenant of Nottinghamshire Sir John Peace attended the garden party where he said the duke had been “telling jokes”.
Speaking of meeting the Queen at the event, he said: “It was wonderful to see the Duke of Edinburgh with her.”
Other than Monday’s cancellation, the duke carried out this week’s engagements as planned.
He was at the Queen’s side at Westminster Abbey on Tuesday for the 60th anniversary of her coronation and on Wednesday toured a Victorian steamship, the SS Robin, in London’s east end.
Ahead of the garden party, the Queen invested Philip with New Zealand’s highest honour, making him an additional member of the Order of New Zealand to mark the Diamond Jubilee.
The Queen is the order’s sovereign and additional members are appointed to commemorate important royal, state or national occasions.
Philip’s citation lists his numerous military posts, patronages and honours associated with New Zealand. They range from his Duke of Edinburgh’s Hillary Award, established in New Zealand in 1963, which encourages and motivates youngsters to become involved in a programme of self-development activities, to his patronage of organisations like the Royal New Zealand Yacht Squadron.