Queen Elizabeth works on as Prince Philip awaits surgery

The 91-year-old Duke of Edinburgh was admitted to the private London Clinic on Thursday evening for what Buckingham Palace said was a planned operation under general anaesthetic.

Queen Elizabeth II visits a studio as she opens the new BBC Broadcasting House yesterday. The new centre cost £1billion. Pic/Getty Images

It was business as usual for the 87-year-old Queen, however, who went ahead with a visit to the BBC's new headquarters just a few streets away from where her husband was being treated. It is the fourth time in two years that Philip has been hospitalised and follows ‘an abdominal investigation that took place last week', a palace spokeswoman said.

The duke, who has been married to the queen for 65 years, is expected to stay in hospital for up to two weeks. The spokeswoman insisted however that Philip was ‘in good health', saying he had walked into the clinic on Harley Street ‘unaided' after being driven there. Although he missed a gala event on Monday, the duke had a full diary of engagements this week and appeared in good spirits as he attended a garden party just hours before going into hospital.