They reportedly don’t get along very well and never have had a great relationship. Now, a documentary seems to be claiming that one incident, in particular, seems to have been the catalyst for Prince Charles and Prince Andrew’s frosty relationship.

The new documentary “The Royal family at War,” claims that things were never great between the two royals, but that the biggest rift came a few years ago after the Duke of York was allegedly sidelined by his older brother during Queen Elizabeth’s Diamond Jubilee celebration in 2012. During the celebration, only six members of the royal family stepped out onto the balcony of Buckingham Palace—Prince Charles and his wife, Camilla Parker Bowles, the Queen herself, Prince William, his wife, Kate Middleton, and Prince Harry. Prince Andrew and his own children were notably missing from the moment.

“It was interesting because the Queen is the only second monarch to have celebrated a Diamond Jubilee. The first being Queen Victoria, so you would expect to see the whole Royal Family on that balcony,” royal commentator Victoria Arbiter said in the film. “It was a momentous occasion, but we didn’t.”

Royal biographer Katie Nicholl also spoke out in the film, stating that it was difficult for the Duke of York to accept that he wasn’t included, because of the clear message that it sent about the future of the monarchy.

“Prince Andrew was very upset. His nose was quite out of joint when he and the other siblings were not a part of that line-up,” she said. “That’s not how Andrew wanted it to be. He wanted to be a part of those balcony appearances. He wants his daughters to be part of the Royal Family but that is the vision that Charles sees and it has certainly led to a fallout.”

It’s been reported that when Charles eventually becomes King, he has plans for a smaller monarchy and slimming down the royal family as a whole, allowing only his immediate family members to be supported by taxpayer money. That move would likely only allow for he and Camilla to be funded, along with Prince William and Prince Harry’s families.

Naturally, Prince Andrew is allegedly furious about it, especially since his daughters, Princesses Beatrice and Eugenie, are the only two blood princesses from the next generation, and he feels they should have a more prominent role, even though they aren’t in any direct line for the throne.

“Andrew is the father of the only to blood princesses of that generation and quite rightfully, he thinks Beatrice and Eugenie have quite a lot to offer,” Arbiter said. “I think Andrew is very keen for his daughters to have a position front and center but Charles isn’t having it, so the brothers are a bit at loggerheads.”

Prince Charles ‘Feud’ With Prince Andrew Started For This Reason Prince Charles and Prince Andrew attend Christmas Day Church service at Church of St Mary Magdalene on Dec. 25, 2017 in King’s Lynn, England. photo: Getty images/Chris Jackson