Martin is the author of standard books and papers on the Art and Religion of Roman Britain and on Roman engraved gemstones. He was awarded a D.Litt. by Oxford University for his academic work. He edited the Journal of the British Archaeological Association 1985-2007 and is now a vice-president of the Association. An ordained priest in the Anglican church, his lifelong passion for animals has led to his vice-presidency of the Anglican Society for the Welfare of Animals, membership of the Board of the Animal Interfaith Alliance and Fellowship of the Oxford Centre for Animal Ethics. Through teaching and example, he aims to counter the speciesism to which human beings are prone.