Prince Philip, 99, is recovering in hospital after a “successful” operation for his pre-existing heart condition.

He was transferred to St Bartholomew’s in London, where he will stay until at least the end of the week.

Buckingham Palace announced on February 17 that “The Duke’s admission is a precautionary measure, on the advice of His Royal Highness’s doctor, after feeling unwell.”

However, their latest statement reads: “The Duke of Edinburgh yesterday underwent a successful procedure for a pre-existing heart condition at St Bartholomew’s Hospital.

“His Royal Highness will remain in hospital for treatment, rest and recuperation for a number of days.”

The palace is currently not commenting on what type of surgery or operation the Duke had at this time, but he had a stent operation on his heart in 2011.

This is his longest hospital stay, as he has so far spent a total of 16 nights being cared for by medics.

Last week, Prince Edward said that he had spoken to his father on the phone and said he was “looking forward to getting out”.

“As far as I’m aware, well I did speak to them the other day, so he’s a lot better thank you very much indeed, and he’s looking forward to getting out, which is the most positive thing,” Edward joked.

“So we keep our fingers crossed.”

This article originally appeared on Over60.