Prince Philip is “OK”, Prince William has said after his 99-year-old grandfather spent a sixth night in hospital.

Philip, the Duke of Edinburgh, was admitted to hospital on Tuesday as a precautionary measure after feeling ill with an ailment that was not related to COVID-19.

“Yes, he’s OK, they’re keeping an eye on him,” William said on a visit to a vaccination centre in eastern England.

Royal reporters said he delivered his message with a wink.

The Duke was admitted to the private King Edward VII’s Hospital in central London after feeling unwell for a short period, Buckingham Palace said, and was kept in over the weekend for further observation.

A royal source said doctors had been acting out of an abundance of caution and that Philip was in good spirits.

Son and heir Prince Charles paid him a brief visit on Saturday, although there has been no official update on his condition since last week.

Philip, who retired…