Prince Philip has been transferred to a different hospital to undergo testing and observation for a “pre-existing heart condition”

A statement from Buckingham Palace also confirmed the Duke of Edinburgh will undergo “testing and observation” for a heart condition, and will remain in hospital for at least another week.

The statement read: “The Duke of Edinburgh was today transferred from King Edward VII’s hospital to St Bartholomew’s hospital where doctors will continue to treat him for an infection, as well as undertake testing and observation for a pre-existing heart condition.

“The duke remains comfortable and is responding to treatment but is expected to remain in hospital until at least the end of the week.”

Prince Philip – who is the husband of Queen Elizabeth II – left the King Edward VII’s private hospital in central London after 13 nights on Monday morning by a back exit, where reports at the scene said he was shielded by umbrellas as he climbed into the back of a waiting ambulance.

The Duke has been visited by several family members - including sons Prince Charles and Prince Edward - since being admitted into hospital.

And Prince Edward, also known as the Earl of Wessex, recently said his father is "looking forward" to getting out of hospital soon but is "a bit" frustrated about staying.

He said: "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 ... Just a bit [frustrated]. I think that gets to all of us, and then you can only watch the clock so many times and the walls are only so interesting. We’ve had some brilliant and lovely messages from all sorts of people and we really appreciate that and so does he, I’ve been passing them on. It’s fantastic, thank you."