Prince Harry and Meghan Markle were "never going to be invited" to the King's birthday celebration in the UK, which takes place this coming weekend, according to reports.
The Trooping the Colour event takes place in London on Saturday (UK time) and will be King Charles' first major public outing after his coronation and since ascending to the throne.
However, it's reported the Duke and Duchess of Sussex - who now live in California in the US after stepping back from Royal working life - would never have been a part of the event which shows off the pomp and pageantry of tradition.
"I don't think they need to be invited," royal historian Gareth Russell told Us Weekly.
"Not as a kind of insult to them, but you know, it's a long trip to make from California for the sake of Trooping the Colour.
"I think this is one of the events where the Sussexes were never going to be invited."
Harry and Meghan attended Trooping the Colour last year, which was part of the late Queen's Platinum Jubilee celebrations.
"Obviously, the coronation was a much bigger event - a generational event, in terms of significance for the royal family," Russell told the magazine, before adding the fact the pair hadn't reportedly been invited shouldn't "necessarily be seen as an indicator of sentiment either way".
Buckingham Palace has also remained tight-lipped on the final guestlist for the parade.
The Trooping the Colour parade will feature hundreds of members of the British Armed Forces and will also include a flypast by the British airforce.
Saturday's event will be the first King's Birthday Parade since 1951 when King Charles' grandfather George VI was on the throne.
Earlier this week, rehearsals for the parade took part in sweltering heat in the UK, leading to several members of the Royal Guard passing out and having to be tended to by army medics.
The procession will include 1400 parading soldiers, 200 horses and 400 musicians moving from Buckingham Palace to the Horse Guards Parade in St James' Park in London.