Some three years later, Prince Philip co-authored a book with Michael Mann called Survival or Extinction: A Christian Attitude to the Environment. The book arose out of a series of gatherings held at St George’s House to discuss the Christian attitude to nature. The discussions were attended by a broad range of delegates, including schoolmasters, research fellows, company chairmen and Philip’s close friend the Duchess of Abercorn, who is described as a ‘Counsellor in Transpersonal Psychology’. The subjects discussed included the danger to the environment arising from scientific and technological advances and from the explosive growth of the world’s population. The book talks about the sacred relationship of all Christians to the source of all life on earth and the urgent need for humans to face up to what they are doing to the planet. Philip’s religious views are again shown to be tied into nature as the book states: ‘Mankind is a fellow creature in symbiosis with the rest of creation, where he has no right to exploit or destroy, but where his kingly status imposes upon him duties to conserve the order of all Creation, for which he is responsible and answerable to God.’

Additional to his views on God and nature, Prince Philip has often stressed the importance of the individual in society, writing in his 1984 book Men, Machines and Sacred Cows: ‘It seems to me everything begins with the individual and it is people who decide what sort of communities they are going to live in. It is the people who are going to decide whether it will be humanly tolerable and civilised or whether it will degenerate into a human jungle . . . Our first responsibility is to be concerned about our own behaviour, our own relationships with other people and our own attitude to what is right and wrong.’

With the Queen and Prince Philip now both into their nineties, their faith continues to play a central part in their lives. For the Queen, her faith is all-important. ‘It’s not just a question of duty for her, it’s very much part of the fabric of her life,’ said a former chaplain at Windsor. ‘She loves matins and the words of the Prayer Book have real meaning for her.’ For Prince Philip, religion has posed many questions for his enquiring mind, as evidenced by his discourses with Michael Mann. Reflecting on those discussions, Mann said Philip could never accept anything until he had chewed it to pieces: ‘When he’s in a corner and he’s lost a point, he does not stop like other people would and say, “Yes, well maybe you’re right,” he goes shooting off on something else, but in fact he will come back later and he will have accepted. You know he has been convinced if he’s changed the subject . . . he would find it very difficult to say: “I’m sorry, I’m wrong.” ’