Two miles down the road from Buckingham Palace’s first royal garden party of the season, Prince Harry walked alone up the stairs of St Paul’s Cathedral. While his father greeted guests, the Duke of Sussex was welcomed to his Invictus Games ceremony by Princess Diana’s siblings – Lady Jane Fellowes and Earl Spencer.

Harry, who flew from Montecito without his wife Meghan Markle, looked overjoyed to see his aunt and uncle inside the cathedral, embracing them with warm hugs and California grins.

They were the only members of his family to attend the Thanksgiving ceremony, which was organised to celebrate the 10th anniversary of the Games. The King’s decision not to attend his son’s event, due to schedule conflicts, was widely perceived as a ‘snub’ against Harry.

Yet, some members of the Duke’s family did attend the event; in the form of Diana’s siblings. The Spencer siblings have remained steadfast in their support of the Prince, throughout his increasingly fractious relationship with the Windsor family. Both Earl Spencer and Lady Jane Fellowes received ‘stand out thanks’ in Harry’s autobiography, Spare – an honour noticeably not bestowed upon his father.

Lady Jane is an especially close confidant for the Duke. She was asked to deliver a speech at his wedding to Meghan Markle in 2018, and she was introduced to the couple’s first son, Archie, before even Prince William. Meghan was touched after Harry introduced her to his aunt, telling reporters before the wedding that she felt like she could ‘know a part’ of Diana through a relationship Lady Jane.

Charles, the ninth Earl Spencer, is a journalist and historian. He is perhaps best known for his own tumultuous relationship with the royal family, pillorying the Windsors and the press during an electrifying address at his sister’s funeral. ‘There never was much love lost between the Spencers and the Windsors,’ according to former BBC royal correspondent Michael Cole, who told MailOnline that ‘the divide was shown in its deepest and starkest form’ as events played out on Wednesday.

Other guests included Rishi Sunak’s wife Akshata Murty, Veterans’ Affairs Minister Johnny Mercer, Harry’s lawyer David Sherborne, and his close friend Mark Dyer – who helped mentor the Prince after the death of his mother. Dyer is also godfather to Meghan and Harry’s son Archie.

Indeed, the physical proximity between St Paul’s and Buckingham Palace served only to highlight the growing schism between Prince Harry and the rest of the royal family. It was thought that the Duke’s trip to London would make the perfect occasion for a reunion with his father (a fraternal reunion with The Prince of Wales never seemed likely following the bombshell revelations in Spare). On Tuesday, however, Harry’s spokesperson announced that there would be no meeting between Charles and his youngest son.

The statement, made to The Telegraph, read: ‘In response to the many inquiries and continued speculation on whether or not the Duke will meet with his father while in the UK this week, it, unfortunately, will not be possible due to His Majesty’s full programme.

‘The Duke of course is understanding of his father’s diary of commitments and various other priorities and hopes to see him soon.’

That diary of commitments, slowly expanding as the King returns to public-facing duties following February’s cancer diagnosis, included the Royal Garden Party, which he hosted alongside Queen Camilla, Princess Anne, Prince Edward, and Sophie, Duchess of Edinburgh.

Mr Cole described the events as ‘quite a snub,’ saying that ‘Prince Harry is bound to see it for what it is, the clearest possible indication of the hurt that has been caused.’

It came on the same day that yet another of King Charles’ engagements was announced: a trip to Middle Wallop’s Army Aviation Centre, where he will hand Prince William the ceremonial title of Colonel-in-Chief of the Army Corps – the regiment Prince Harry served with in Afghanistan. The honour was long considered to be Harry’s in all but name.

Royal experts noted that the Duke’s uniform might have signalled a subtle retaliation. Alongside a medal bestowed upon him by his late grandmother, Queen Elizabeth, Harry donned his KCVO Neck Order and Star, awarded for services to the monarchy. Notable by its absence was the King’s Coronation Medal – the second time he has gone without the award, handed out to those involved in Charles’ 2023 Coronation service.

Despite a few boos, the Prince was warmly received outside St Paul’s by crowds – said to include ‘many tourists’. He laughed with onlookers, taking photos and cracking jokes before being welcomed into the cathedral by the Dean of St Paul’s, the Very Reverend Andrew Tremlett. The Dean gave a speech celebrating the work of the Invictus Games, which helps injured veterans with their physical and mental recovery after service.

‘We recall, with admiration, the skill and determination of those who seek to repair, rehabilitate, and reclaim the lives of those living with serious illness or injury,’ read the Dean.

The Invictus poem was read by actor Damian Lewis, and the UK Invictus Team vice-captain, Michelle Turner, gave a moving rendition of a personal poem, recounting how the games helped her and her family while she recovered.

The Prince had spent the evening before the event having dinner with his friend and former Invictus Games Foundation trustee, Guy Monson. After leaving St Paul’s, Harry will fly to Nigeria for a tour further celebrating the Games’ anniversary. He will be joined there by the Duchess of Sussex.