The British royal family is getting more concerned for Prince Philip as he continues to remain in the hospital in what is his longest stay ever.

On Monday afternoon, the Duke of Edinburgh was moved from the private King Edward VII hospital in Central London to St Bartholomew's, Britain's oldest hospital near St Paul's Cathedral. The staff held up umbrellas to ensure his privacy as he was carried by stretcher to a waiting ambulance.

A palace statement said that doctors will continue to treat the Duke "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," the statement added.

St Bartholomew's Hospital, commonly known as Barts, is a specialist in cardiac care, containing Europe's largest specialised cardiovascular service. According to a report in The Mirror, the Duke's transfer to the hospital has darkened the mood at Windsor Castle, where he was staying with his wife, Queen Elizabeth II until his hospitalisation.

A royal source said: "The staff and all the Royal Family are united in their prayers for the Duke. There has been an almighty and collective effort to keep him and the Queen safe during the coronavirus crisis over the past 11 months but there was a significant shift in the mood when everyone started finding out the Duke wasn't coming home any time soon."

"Everyone's thoughts are now firmly centred on him pulling through this illness," the insider added.

The hospitalisation comes at a time when Buckingham Palace was busy in the preparations for Prince Philip's milestone 100th birthday celebrations in June. Unfortunately, medical experts have warned that the British royal, who retired from public duties in 2017 at the age of 96, could be kept in the hospital for another six weeks. The 99-year-old was first admitted to King Edward VII hospital on February 16 as a "precautionary measure," and it was later revealed that he is suffering from an unknown infection.

The recent health battle is the longest hospital stay to date for the Prince Consort who was previously treated for a blocked coronary artery in 2011 at Papworth Hospital where he had a stent inserted. His hospital visits in his younger days were largely limited to sports injuries. In 1987, he was hospitalised for a hernia repair, while a small benign growth was removed from his nose in 1996.

Prince Philip
Prince Philip, the Duke of Edinburgh. Photo: POOL / Adrian DENNIS