Mark Powell has been diving since 1987 and instructing since 1994. He operates Dive-Tech a company teaching technical diving for several leading agencies at all levels up to and including Advanced Trimix. He is a contributor of Sport Diver Magazine and has a monthly Technical feature discussing different aspects of technical diving.

John Flower is Emeritus Professor of Twentieth Century French Literature at the University of Kent. Flower has published extensively in the UK and in France, with more than twenty single-authored books, seventy articles and invited contributions, and a dozen edited volumes.

His work covers French literature and culture since the late nineteenth century. He has also published a study of Joan of Arc as interpreted by novelists, poets, dramatists, composers and film producers. He is a member of various editorial boards, and is the founding and general editor of the Journal of European Studies.