Wildlife expert and broadcaster Sir David was one of the guests invited to talk about their memories of Prince Philip during BBC One's programme ahead of the funeral service beginning.
He said: “He was right there at the beginning at a time when conservation didn’t mean much to many people. Even in the 1950s and 60s he saw it universally.
"The World Wildlife Fund owed a huge amount to his presence. When he spoke about conservation, he spoke about it with passion and knowledge.”
Sir David added: "If people are aware that there are problems (with wildlife conservation), a great deal of that is due to him."
The naturalist admitted that it could be nerve wracking to be in the Duke's presence, but said that he was also a "cheerful" man to be around.
He said: “He was an extraordinary combination of being formidable and friendly. You knew he was there. He had an amazing presence. It was an extraordinary balancing act between formality and informality.”
Also sharing his memories of Prince Philip was gardener and broadcaster Alan Titchmarsh, who read out an excerpt from a humorous letter the Duke had sent him about his hobbies, which included shooting and carriage driving.
Read more: Prince Philip's funeral in pictures
Former Royal Marine and TV presenter JJ Chalmers was another of the familiar faces fronting BBC One's coverage, as he spoke about the military involvement in the ceremony and the Duke's naval career.
Prince Philip's funeral is taking place at St George's Chapel in Windsor Castle, with a congregation of just 30 mourners because of coronavirus restrictions.
Watch: William and Harry pay tribute to the Duke of Edinburgh