How Prince Charles honoured beloved late great-uncle Lord Mountbatten on his wedding day

It is well known that Prince Charles shared a close relationship with his great-uncle Lord Louis Mountbatten, 1st Earl Mountbatten of Burma. Mountbatten, who was a maternal uncle of Charles's father Prince Philip, Duke of Edinburgh, and second cousin once removed of his mother Queen Elizabeth II, served as a mentor and a close confidante for the heir apparent.

Mountbatten was assassinated by the IRA in 1979, two years before the Prince of Wales wed Lady Diana Spencer. To honour his late great-uncle at his wedding, Charles requested his bride to include the Mountbatten rose in her bridal bouquet. Florist David Longman, a member of the Worshipful Company of Gardeners who created the floral arrangements for the 1981 wedding, shared the anecdote in a new Royal documentary "The Wedding of the Century" that premieres on BritBox on Thursday.

"The Prince made one request and that was a Mountbatten rose in memory of his uncle, who he was very attached to. He particularly wanted it. There was only one grower. It's not really a florists' rose - it's a garden rose. And it was only one colour because it's a golden rose there in the centre of the bouquet," he revealed.

The florist also recalled the intricate process of preparing the bouquet for the iconic wedding, which was set to introduce the country to its new Princess of Wales and the future Queen consort.

"My conversations with Lady Diana were very similar to so many discussions I had with brides and what they wanted. I showed her the designs – we had many more designs and more intricate designs than I would show to a normal bride. We talked to the dressmaker beforehand. I had been to see the dressmaker," Longman said.

Longman revealed that the wedding gown designers, Elizabeth Emanuel and David Emanuel were "very discreet" as they had to keep the design secret, and didn't tell him very much about it. However, they gave him a patch of material so he could feel what it was going to be like. "And they showed me an outline sketch so I knew it was going to be a very voluminous dress," he said.

Recalling the late Princess Diana, Longman said, "she was like any other bride, excited, intrigued, wanting guidance as to what she was to have, very normal, a very, very normal young bride. She chose this one, which was a long drop bouquet, lily of the valley, stephanotis, orchids."

Longman, whose father had created the floral bouquets for both Queen Elizabeth II and her sister Princess Margaret's weddings, revealed that Diana was "always charming, very easy to deal with," and wasn't "particularly demanding," but had only one special request. The Princess had noticed in a picture from the wedding of her mother-in-law, the Queen, that the bride was the only one without a bouquet while posing with all the bridesmaids. This was because the Queen, then Princess Elizabeth, had asked for her bouquet to be put on the tomb of the Unknown Warrior.

Longman recalled, "Lady Diana had heard this story so she said: 'Please can we have two bouquets?' So, we had one that went straight onto the tomb and the other that was delivered to Buckingham Palace ready for the photographs."