Eventually they realised that I was badly designed for understanding maths or sciences so I was switched to languages, and Mr Callender taught me French, English and German after school in a small group at his home. He was so good at his job that I actually found, for the first time, that I was competent at something. I enjoyed German and was good at it, and I discovered I had a talent for writing.
One project he set was to select a book and precis the whole thing in a certain number of words. I chose the autobiography of a Russian Englishmen, Serge Obolensky, called One Man in his Time, and I had about a week to reduce around 100,000 words to 2,000. I found it challenging and satisfying, and being used to teachers being honest, and therefore rude, about things I did, I bathed in the genuine praise I got. It gave me confidence and I thought: "Gosh, I'm going to be good at English," and I realised I could write. Everything I have done since has been thanks to Mr Callender's inspiration.
Before I came under his tuition, I had a sense of failure at school. I didn't think I was ever going to get one O-level, never mind five. I eventually got four, but I didn't manage any A-levels, even though I went to a crammer. I never got to Sandhurst. Instead, I took a short service commission and joined the Royal Scots Greys and, later, the SAS.
About a year after I left Eton, I went back to the school with some friends and disrupted the Fourth of June celebrations. The night before the famous fireworks and procession of boats, we laid ropes and hooks using underwater equipment. Then, when the Eights stood up in their narrow boats to throw their hats into the air, we livened up the proceedings by overturning their craft.
Unfortunately, my diving equipment went wrong and I shot to the surface and was chased by a couple of motorboats driven by the Etonian river masters - one of whom was Mr Callender. I headed for the bank and some overhanging trees, where I got rid of the air cylinder. I found running difficult in a frog suit, so when a group of senior boys was put ashore to chase me, I lay in a deep puddle, with my nose just above water level. Eventually I got back to the car and changed.
Unfortunately, the abandoned air cylinder, which I had borrowed from my girlfriend (now my wife), had a number on it and I thought I would be in trouble from my prospective father-in-law, and others, if it was found. I fooled one of the boys into giving me a lift to pick it up by saying I was an Eton boy and I'd seen some hoodlums with an air bottle on the other bank and I was going to take it back to Mr Callender. Because I was able to mention his name, they believed me, and I got away with it.
About 15 years later, I told this story in one of my books, and some years after that, when another of my books became a bestseller, Mr Callender wrote to me and invited me to visit. He was friendly and charming and we laughed about the incident with the boats, but I'm not sure he had always laughed about it.
Explorer Ranulph Fiennes was talking to Pamela Coleman
THE STORY SO FAR
1944 Born in Windsor
1956-60 Attends Eton
1960 Attends a crammer in Hove, fails A-levels twice
1962 Joins the Army's Royal Scots Greys regiment
1965 Posted to the SAS
1967 First expedition - to the Nile by hovercraft
1968-70 Serves with the army of the Sultan of Oman
1982 With Charlie Burton, becomes first explorer to reach both Poles
1991 Completes first unsupported crossing of Antarctic
1993 Leads expedition to locate the lost city of Ubar in Oman
October 2001 Publication of a novel, The Secret Hunters (Little Brown)
November 2001 Completes endurance race, Southern Traverse, in New Zealand