Queen Elizabeth II, Britain's longest-reining monarch who died at the age of 96, was "more than just a friend for 35 years," says the queen's horse trainer, Monty Roberts.

After attending the queen's funeral service at Windsor Castle on Monday, the 87-year-old shared that he spent a lot of time in the castle but had "never seen it like that. It was just a different world."

"Queen Elizabeth has been more than just a friend for 35 years," Roberts said, as reported by People on Tuesday. "I was worried about being emotionally disturbed at the funeral — a lot of people do. I was worried about crying."

During the funeral, Roberts recalled, his wife asked him to sit down because she thought he was going to fall as he had trouble standing for too long due to an auto-immune condition.

He went on to share the emotional moment when he saw the coffin.

"When they brought in the coffin, I stood up and told myself, 'You're not going to cry,' then it hit me," he added. "And the water just started running out of my eyes. I thought, 'What is this?' It was really tough on me."

Roberts went on to share what he learned when he discussed his feelings with a surgeon friend, "It's inner sadness or anxiety that you couldn't hide — and the water just runs straight out without you gasping or crying in the usual way."

The horse trainer added, "He made me feel a lot better because I do have inner sadness."

The royal family and close friends paid their final tribute to the queen Monday and Roberts, who is originally from California, said the atmosphere felt "reverent" in the chapel. "Everybody felt it was a proper way to send her away," he added.

Here are a few glimpses of the queen with horses shared by various Twitter users:

During the funeral, the queen's horse groomer Terry Pendry also accompanied Roberts.

"He has been such an incredible asset to her life and stable," Roberts said about Pendry. "I don't know how Terry did it today. He was as good as gold. He hosted us afterward, and he was okay. He was smiling and laughing — he's handled it very well."

Britain's Queen Elizabeth reacts as she watches horses competing on the second day of the Royal Windsor Horse Show and Platinum Jubilee Celebration in Windsor, Britain, May 13, 2022.
Britain's Queen Elizabeth reacts as she watches horses competing on the second day of the Royal Windsor Horse Show and Platinum Jubilee Celebration in Windsor, Britain, May 13, 2022. Reuters / TOBY MELVILLE