The 99-year-old, who will turn 100 in June, was initially due to spend a few days under medical care for “observation and rest”. He is now into his eighth day at the private hospital.
Today, his son Prince Edward told Sky News that his father is “a lot better” and he is “looking forward” to getting out of hospital.
The duke received a visit from his eldest son, the Prince of Wales, on Saturday – a rare occurrence as the duke is known for his “no fuss” attitude.
William was asked about the duke’s health when he visited a vaccination centre in Norfolk on Monday, and replied “Yes, he’s OK, they’re keeping an eye on him”, and gave a wink.
Sources have said that Philip’s doctor is “acting with an abundance of caution”.
Members of the royal family have continued with their duties since the duke was taken to hospital.
Philip has been spending the latest lockdown with the Queen at Windsor and in January they both received Covid vaccinations.
The duke last had a spell in hospital in December 2019, when he was treated for a “pre-existing condition” and discharged on Christmas Eve after four nights.
This story is being updated.