Prince William joins Charles and Queen Camilla at Garter Day service

Prince William chatted with his uncle Prince Edward during the Order of the Garter procession this afternoon as they joined the King and Queen at Windsor Castle.

Charles and Camilla led members of the Royal Family to the annual Garter Day service at St George’s Chapel as the busy royal summer period began in earnest.

Other royals at the traditional celebration commemorating the ancient Order of the Garter included Princess Anne, Sophie and the Duchess of Gloucester.

The King’s appearance comes just two days after the Trooping the Colour ceremony in London where he was joined by fellow cancer patient the Princess of Wales. But Kate did not attend today’s service, and her chemotherapy treatment continues.

Queues lasting more than two hours had built up outside the castle this morning, with visitors bringing camping chairs as they prepared for a long wait to get in. 

While the main castle was shut to the public today, people queued to get a glimpse of those attending the service from 3pm at St George’s Chapel within the grounds.

The line went all the way down St Albans Street next to the castle and up to Park Street, with castle staff trying to keep everyone entertained in the sunshine.

One local resident told MailOnline that the queue was ‘going back almost to the Long Walk’ and the number of police officers in the area was ‘more than doubled’.

He added: ‘Since King Charles and the Princess of Wales had their cancer announcements, Windsor Castle has never been so busy.

‘Now the bulk of them seem to be American tourists flocking back over. They’re all hoping for a glimpse of King Charles when they go round the grounds.

‘This has probably been the record this year and probably since the Queen’s death. This is just a regular week, it’s nice weather but it’s not boiling hot.

‘Even in the rain back in March and April they were queuing up for ages under their umbrellas. Today was unusually busy because of the Garter.’

After the snap General Election was called last month by Prime Minister Rishi Sunak for July 4, Buckingham Palace said the Royal Family would postpone engagements ‘which may appear to divert attention or distract from the election campaign’.

However, this was not a blanket ban and visits are being considered on a case-by-case basis – with the Garter Day service among the events given the go-ahead.

Garter Day sees Ladies and Knights of the Order of the Garter – the country’s oldest and most senior Order of Chivalry – process down the hill from the Berkshire castle’s State Apartments to St George’s Chapel, dressed in white plumed hats and dark blue velvet robes, watched by crowds of onlookers.

The palace said Charles, Camilla and members of the Royal Family will depart by carriage afterwards and return to the castle.

The installation of new Companions of the Order – including composer Andrew Lloyd-Webber who has been made a Knight Companion – will take place during the service. 

Theatre impresario Lord Lloyd Webber, whose hit musicals include The Phantom Of The Opera, Cats, Jesus Christ Superstar and Joseph And The Amazing Technicolor Dreamcoat, also attended a private investiture in the castle’s Garter Throne Room earlier today.

Also being invested was the Duchess of Gloucester as a Royal Lady of the Garter, as well as Lord Kakkar, emeritus professor of surgery at University College London and Air Chief Marshal the Lord Peach, who have both been made Knight Companions.

The Order of the Garter was established nearly 700 years ago in 1348 by King Edward III who was inspired by tales of King Arthur and the chivalry of the Knights of the Round Table.

The Garter is awarded by the sovereign for outstanding public service and achievement.

Last Thursday, Buckingham Palace announced that Baroness Manningham-Buller, the former director general of MI5, had been named as the Order of the Garter’s new Chancellor.

Lady Manningham-Buller, who served for more than 30 years with the intelligence service including five years as its director general, was appointed to the role by the King.

The decision is the King’s gift, made without consulting ministers, and from today the peer becomes the first woman to hold the post since the office’s inception in 1475, and will succeed the Duke of Abercorn, retiring after 12 years.

Lady Manningham-Buller sits as a crossbench peer in the House of Lords and was appointed a Lady Companion of the Most Noble Order of the Garter by Queen Elizabeth II in 2014, after she retired from MI5 seven years earlier.

The main focus of her work with MI5 was counter-terrorism, both international and domestic, and during her tenure terrorists launched the July 7 bombings in London and terrorism risk assessments were made public. 

Charles also appointed Lord Ashton of Hyde, a former Conservative chief whip in the Lords, to the largely ceremonial role of Master of the Horse.

The holder in centuries past was responsible for the sovereign’s horses, coaches and travel arrangements and today is titular head of the Royal Mews, which looks after royal vehicles such as state Bentleys and carriages.

Lord Ashton will replace the serving Master of the Horse, Lord de Mauley, whose final major duty was to ride in Trooping the Colour ceremony as holders of the post are present when the Royal Mews supports state occasions.

It comes after Charles’s official birthday celebrations on Saturday, where the Princess of Wales made her first public appearance this year.

Kate looked relaxed during her first day in the spotlight following her cancer diagnosis for the traditional Trooping the Colour ceremony.

With the King also suffering from cancer, it was a rare joint public outing for the entire family after a period of uncertainty.

Kate rode to the event in a carriage with her children, while William, the Princess Royal and the Duke of Edinburgh were on horseback.

The King also rode in a carriage with the Queen, a departure from last year because of his illness.

Both Kate and Charles have thanked the public for their support after going public with their illnesses, with Kate saying she had been ‘blown away’ by the ‘kind messages’ that had made a ‘world of difference to William and me and has helped us both through some of the harder times’.

Kate was initially admitted to hospital for abdominal surgery on January 16 and at the time her condition was thought to be non-cancerous, but cancer was found following the successful operation.

Charles was admitted to hospital just days after Kate, also for a procedure deemed unrelated to cancer.

In February, Buckingham Palace confirmed that he had been diagnosed with a form of cancer, which is not prostate cancer, that was discovered while the King was being treated at the private London Clinic for an enlarged prostate.

Charles initially postponed public-facing duties but resumed at the end of April, speaking of his ‘shock’ at being diagnosed with cancer as he met patients during a visit to University College Hospital Macmillan Cancer Centre in central London.