It was decided they should eat a light lunch before leaving for the airport and, much to Philip’s irritation, Charles disappeared. He obviously needed to be alone so that he could face whatever lay ahead, but Philip sent Lord Mountbatten’s private secretary, John Barrett, to find him. When Barrett saw the prince standing there, head bowed, shoulders drooping, he didn’t have the heart to disturb him. When Charles eventually returned to the table, his father baited him until his son got up and left the room. Both the guests and staff were embarrassed and found it extremely distressing. The duke was trying to stiffen his son’s backbone, but for a man who is a Christian he was and still can appear to be very cruel. He simply refuses to accept any weakness, though if Prince Charles had instead discussed some theological point about the soul of the man he so loved, Philip would have joined in.

Over a period of more than thirty years, the Duke of Edinburgh has engaged successive deans of Windsor in wide-ranging philosophical discussions. These have been on the meaning of life, the purpose of man on earth, science and religion, Charles Darwin and the origins of man and, perhaps most important of all to Philip, the relationship between man and nature.

His querying mind has even taken him to some fairly unusual areas. In earlier times, following discussions with Mountbatten, Philip picked up on his uncle’s interest in UFOs. He took out a subscription to Flying Saucer Review and entered into a correspondence with Timothy Good, a worldwide authority and author of several books on the subject. Philip wrote to him: ‘There are many reasons to believe that they exist. There is so much evidence from reliable witnesses.’

In July 1986, Philip, as President of the World Wide Fund for Nature, gathered together representatives of the world’s five major religions for the WWF twenty-fifth anniversary conference. At the suggestion of Prince Philip, the conference was held at Assisi, the home of St Francis, patron saint of birds and animals. The idea was to link the secular movement for the conservation of nature with the religious perception of nature as the creation of a supreme being. Philip wrote: ‘Most if not all religions allow for some measure of divine intervention in the creation of the world and in the operation of the natural system. Therefore, if God is in nature, nature itself becomes divine, and from that point it becomes reasonable to argue that reverence for God and nature implies a responsibility not to harm it as a duty to the Creator.’ The conference was a success in that the leaders of the religions involved each issued a declaration regarding the importance of our relationship with the natural world. Philip believes that there is a moral imperative recognised by all the great religions to support conservation.