Rare photos from 1980 show Princess Diana and Camilla, Queen Consort, supporting King Charles III at a horse race

• Princess Diana and Camilla, Queen Consort, were photographed together in 1980.
• At the time, both women were attending a horse race to support King Charles III.

Photos from four decades ago show Princess Diana and Camilla, Queen Consort, together during a rare moment.

The rocky relationship between Diana and Camilla has long been speculated about, but in 1980, the two women were united for a common purpose — to support King Charles III.

Diana – then Lady Diana Spencer – and Camilla were pictured arriving at Ludlow Racecourse in England to watch Charles compete in the Amateur Riders Handicap Steeplechase. The photos appeared to show the pair walking and chatting together prior to, and during the competition.

In the years that followed, the relationships between Diana, Camilla, and Charles made headlines.

Insider's Anneta Konstantinides reported that Charles and Camilla first met in 1970 when Camilla introduced herself to Charles by saying: "My great-grandmother was the mistress of your great-great-grandfather. I feel we have something in common."

Royal expert Marlene Koenig told Insider that Charles and Camilla had an instant attraction, prompting their friendship to turn romantic over the course of 18 months.

However, Charles left in 1972 to serve in the Royal Navy, and, the same year, Camilla married her on-and-off again boyfriend, Andrew Parker Bowles. Charles and Camilla remained friends even after Camilla had two children in 1974 and 1978.

In 1977, Charles met Diana and they later married in July 1981.

Diana told journalist Andrew Morton, who wrote the 1992 biography "Diana: Her True Story," that Camilla viewed her as a "threat" when they first met in 1980.

"[I met her] very early on. I was introduced to the circle, but I was a threat. I was a very young girl but I was a threat," Diana told Morton.

She later told Morton that she was unhappy on her wedding day, which was dubbed the "Wedding of the Century." However, Charles and Diana's marriage began to crumble over the next several years. Charles reconnected with Camilla in 1986, leading Diana to confront Camilla about the affair.

"I said, 'I know what's going on between you and Charles and I just want you to know that," Diana said, recounting her conversation with Camilla. "She said to me: 'You've got everything you ever wanted. You've got all the men in the world fall in love with you and you've got two beautiful children, what more do you want?' "So I said, 'I want my husband.'"

Camilla and Andrew Parker Bowles divorced in 1995, while Charles and Diana divorced in 1996. One year later, Diana died in a tragic car crash. Charles and Camilla didn't make a public appearance until 1999, but later moved in together in 2003 and wed in 2005.

Koenig told Insider that the Queen gave a toast in front of 800 people at Camilla and Charles' wedding reception.

"They have come through and I'm very proud and wish them well," Queen Elizabeth II said. "My son is home and dry, with the woman he loves."