My grateful thanks to all without whom this story and web page would not exist:-
The Sisters of St Mary's Abbey, West Malling, Kent, for giving me first-hand experience of a "secret passage" of unknown date in their garden;
Tony Glover, Head of Classics, Bexley Grammar School, Welling, Kent, for his help with the Latin inscription;
Friends and colleagues at London Electricity, Bexleyheath, Kent in the early 1990s;
Keith Hallock, for the HTML code and for teaching me FTP.
Not forgetting:
The late great M R James:
"The Treasure of Abbot Thomas" from "Ghost Stories of an Antiquary", originally published in hardback by Hodder & Stoughton Limited, Mill Hill Road, Dunton Green, Sevenoaks, Kent, TN13 2YA.