Peter Phillips has expressed his sadness as he announced that his family-founded event, The Festival of British Eventing, is unable to take place this year.
The equestrian event which has been held at the Princess Royal's Gloucestershire home, Gatcombe Park, since 1983.
But rising costs have made the festival "unviable" to run in 2024.
In a statement, event director Peter, 46, said: "It is with a heavy heart that The Festival, which has played a significant part in the British Eventing calendar since 1983, cannot run this year. The event has also been a huge part of my family’s lives and those of many others for 40 years.
"It has built up a large community that has enjoyed and celebrated The Festival each year. I would like to thank everyone who has been involved over the past four decades; our sponsors for their unwavering support, the large selection of trade stands and arena entertainment and our spectators who have loved coming to Gatcombe to watch the world-class equestrian sport from the famous Park Bowl."
Peter's father and event chairman, Captain Mark Phillips, 75, added: "The horse trials at Gatcombe and more recently the Festival of British Eventing have been a major part of my life for over 40 years when The Princess Royal and I first had the dream.
"The dream became reality, and with it, many special memories of the many riders, horses, volunteers, sponsors and spectators all of whom massively contributed to the history of the horse trials at Gatcombe Park."
© GettyHe added: "It's truly a great sadness that the original model and indeed the sport has changed so much. Since Covid, costs, particularly insurance, have risen so much that the numbers no longer add up. It is an end of an era, the next 40 years of the sport will be different, let’s hope it can be equally special."
It comes after the final day of the 2023 event had to be called off due to adverse weather.
© GettyPeter, who shares daughters Savannah, 13, and Isla, 11, with his ex-wife Autumn, is head of partner acquisition for the sports and entertainment rights agency CSM Sport & Entertainment.
He and his sister Zara Tindall and her husband, Mike, attended the F1 Grand Prix in Bahrain over the weekend, alongside Peter and Zara's cousin, Princess Eugenie.
