My grateful thanks to Zoë Swenson-Wright for her unerring eye and detailed advice; to Jas and Sylvie Elsner for the inspiration; to my editor Robin Robertson and my agent Lucy Luck for support and suggestions; to Nick Miedema for his reflections; to Mike Lewis for allowing me to plunder his paper on imperial hydraulics; to Alexis Abbou, Bernard Pignero and Didier Goethals for their help and friendship; to Alex Bowler, Hannah Ross and all at Jonathan Cape; to Sylvie Wheatley for her last-minute advice; to all those who gave me technical help on everything from swimming pools to electric fences; to Aimé Vielzeuf, ancien Résistant, for his published war memories –and to those who have, over the years, recounted similar experiences to me in conversation; to my late father Barney Thorpe for his Francophilia and much-missed enthusiasm; to Josh, Sacha and Anna for the guidance of youth; and above all to my wife Jo for her patience and wise counsel.