King Charles and Queen Camilla may be about to give the "wedding of the year" a miss, after they've apparently failed to RSVP with only three weeks left to go. It's reported that the duo has yet to confirm attendance at the upcoming nuptials between Duke of Westminster, Hugh Grosvenor, and his future wife Olivia Henson.

The delay in decision-making has stirred rumours of strife among the families, particularly due to memories of King Charles and Queen Camilla declining an invitation to the marriage of the duke's sister, Lady Tamara Grosvenor back in 2004.

Lady Grosvenor exchanged vows with Edward van Custem, a godchild of His Majesty, at Chester Cathedral, interestingly enough, the same venue for this year's anticipated wedding. This followed an instance where Camilla, then known by her previous name Parker Bowles, was instructed not to sit beside Prince Charles and to be seated several rows behind, entering the ceremony separately.

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The reason for this was the attendance of Queen Elizabeth and Prince Philip, as well as Princes William and Harry. According to a source cited by Richard Eden, MailOnline's Royal correspondent: "Their Majesties have not forgotten what happened at the wedding of Hugh's sister. There is still a lot of tension that exists."

Royal author Sarah Bradford has revealed that the Queen was so incensed over a particular situation that she informed Prince Charles that the existing arrangements were no longer tenable. An insider at the time disclosed: "Her Majesty is a stickler for protocol. It would be inappropriate for Mrs Parker Bowles to sit beside Prince Charles since she has no official standing.", reports the Mirror.

The atmosphere was further strained by allegations that Emilie van Cutsem, mother of the groom, and Camilla had a falling out after purportedly criticising each other's children's conduct. With only days remaining before the event, Charles excused himself, citing a need to visit Warminster barracks to engage with families of soldiers stationed in Iraq, while his companion was said to be 'otherwise engaged'.

Charles and Camilla have reportedly not responded to their invite, with the wedding just three weeks away
File photo: King Charles and Queen Camilla have reportedly not responded to their invite, with the wedding just three weeks away

Despite Hugh being rumoured to be the godfather to their son, Prince Archie, the Duke and Duchess of Sussex have been notably left off the guest list for next month's wedding. It is thought that the duke is concerned that extending an invitation to the couple, who apparently received a save-the-date email by mistake, might heighten tensions within the Royal Family.

A source close to the Sussexes later stated: "Harry called Hugh and said it would be too awkward if he and Meghan Markle attended, so he made his apologies and Hugh understood."

The Prince and Princess of Wales, along with their eldest child, Prince George, who is also one of Hugh's godchildren, are expected to attend the nuptials. However, Catherine is unlikely to be present as she is currently receiving treatment for cancer.

A spokesman from Buckingham Palace declined to comment.