Daily Mail Online: LONDON, England – The Duke of Edinburgh arrived back at Windsor Castle today after leaving hospital following a month under the care of medical staff after being admitted with an infection and later undergoing heart surgery.

Prince Philip, 99, the nation’s longest-serving consort, spent 28 nights as a patient in London at King Edward VII’s Hospital and St Bartholomew’s Hospital – his longest ever stay. Philip was initially admitted on a precautionary basis for an infection, before having a heart operation midway through his four-week period in hospital.

The ‘Iron Duke’ was photographed leaving King Edward VII’s Hospital in Marylebone at about 10.30am today, with screens obscuring him in a wheelchair for the most part, before getting into a car and being driven away.

Philip, who is set to celebrate his 100th birthday in June, headed to Windsor Castle to be reunited with the Queen after a month without seeing her, arriving within less than an hour. Sources said the Duke was in “good spirits”.

A Buckingham Palace spokesman said in a statement issued at about 11.45am today: “The Duke of Edinburgh has today been discharged from King Edward VII’s Hospital and has returned to Windsor Castle, following treatment for an infection and a successful procedure for a pre-existing condition.

“His Royal Highness wishes to thank all the medical staff who looked after him at both King Edward VII’s Hospital and St Bartholomew’s Hospital, and everyone who has sent their good wishes.”

The Duke was initially taken by car to King Edward VII’s Hospital on February 16, after telling his doctor he felt unwell. But two weeks later he was moved to St Bartholomew’s Hospital in the City of London by ambulance.

Philip will have much to catch up on with the Queen following a dramatic week that saw the Duke and Duchess of Sussex plunge the monarchy into a crisis by accusing a member of the Royal Family of racism – not the Queen or Philip – and claiming that Meghan Markle received no support with her mental health problems.

The Duke of Edinburgh underwent a successful procedure on a pre-existing heart condition at Barts on March 3, before returning to King Edward VII’s Hospital a few days later to recuperate and continue his treatment.

The Duke of Edinburgh leaves King Edward VII's Hospital in London today following a month of treatment by medical staff

A convoy carrying the Duke of Edinburgh arrives at Windsor Castle in Berkshire this morning

Prince Philip leaves King Edward VII's Hospital in London this morning having spent a month being treated

A screen is placed outside King Edward VII's Hospital in London today where medical staff have been treating the Duke

Police officers outside King Edward VII's Hospital in London where the Duke of Edinburgh has been receiving treatment

Concern about the Duke of Edinburgh has been heightened because of his advanced age and his hospital stay comes amid troubled times for the royal family.

Philip has been treated for heart problems in the past and in 2011 was taken to hospital by helicopter from Sandringham after suffering chest pains as the royal family was preparing for Christmas.

He was treated for a blocked coronary artery at Papworth Hospital in Cambridgeshire and underwent a minimally invasive procedure of coronary stenting.

The duke had been spending the latest lockdown at Windsor with the Queen for their safety, alongside a reduced household of staff dubbed HMS Bubble.

The couple, who have been married for 73 years, received their first COVID-19 jabs in January.Prince Philip is pictured during the transfer of the Colonel-in-Chief of The Rifles at Windsor Castle on July 22, 2020

How private King Edward VII’s Hospital is the first choice for the royal family

Many a royal has been cared for at the private King Edward VII’s Hospital.

From the Queen to the late Princess Margaret and the Queen Mother, the exclusive clinic in central London has been the first port of call for ailing members of The Firm for years.

The Duke of Edinburgh has been admitted a number of times in recent years and the Duchess of Cornwall had a hysterectomy at the medical institution in 2012.

The first time the Queen was admitted to hospital was at the King Edward VII’s in July 1982 when she had a wisdom tooth extracted.

In 2003, the clinic’s surgeons also removed minor non-cancerous growths from the monarch’s face and operated on her knee.

Tragedy struck in 2012 when nurse Jacintha Saldanha apparently killed herself after she was duped by two hoax callers who had phoned the hospital.

The Duchess of Cambridge was being treated at the hospital for severe morning sickness when pregnant with Prince George, and Ms Saldanha – believing the Australian pair were senior royals – put them through to a colleague who described in detail Kate’s condition.

Philip was treated at the hospital for a short period in 2018 following a planned admission for a pre-existing but undisclosed condition.

The previous year the duke spent nine days receiving treatment and physio following a hip replacement at the institution.

King Edward VII’s Hospital was established in 1899 by two sisters, Agnes and Fanny Keyser, who turned their home at 17 Grosvenor Crescent into a hospital for sick and wounded officers returning from the Boer War.

King Edward VII became the hospital’s first patron – a role now held by the Queen. Edward VII, Charles’s great-great grandfather, had an affair with Camilla’s great-grandmother Alice Keppel.

The hospital moved to its present site in Beaumont Street in 1948, and in 2000 it changed its title to King Edward VII’s Hospital Sister Agnes.