My business career began at school. From the age of 12, I was flogging stuff to the other kids. I'd go to the army surplus store and buy massive rolls of 35mm film which was past its sell-by date but still suitable for amateur work, cut it into bits and put them into little canisters and sell them at half the price you'd pay for new film. I also sold transistor bits and radio bits. By the time I was 15, I was earning more money at school than my dad was earning going to work five days a week. The school thought I was very enterprising, and when they needed something selling, like the school magazine or raffle tickets, they got me to do it.
I enjoyed my schooldays. I went to Joseph Priestley in Clapton, which later became Brooke House comprehensive, and I had some good teachers, although none of them could be described as a mentor. I liked science, particularly chemistry. Victor Pollard was a professional pharmacist as well as my chemistry teacher, form teacher and house master. He really knew his stuff.
I remember learning how to make gunpowder from iron filings, saltpetre and sulphur and demonstrating how it ignites in a special flameproof chamber.
Later on I enjoyed what was called "spots" where you were given an unknown compound and had to work out what it was made from using a series of experiments and tests.
I liked lessons in which there was something to see and do. In Mr Brown's physics lessons, I remember learning a bit of electrics, Ohm's Law, Archimedes' principle and getting metal balls on string to move from side to side. I also enjoyed engineering, woodwork and technical drawing, though I can't remember the names of the masters who taught them.
I remember Mr Grant, the maths master, because even though he gave up on me, I managed to pass my O-level. He was a real eccentric. We used to call him Theta Grant because he made us laugh when he wrote the Greek letter theta on the blackboard. He was accident-prone. He'd come into school with his face smashed in or a broken arm. There were all sorts of rumours going round, but we never found out the cause of his injuries.
When I discovered that the maths O-level syllabus involved something called calculus, which was supposed to be really difficult, I was fascinated. I've always enjoyed a challenge. I'm a quick learner and have a photographic memory. Within three or four weeks, I became the whiz-kid of calculus, which got me through the exam. Grant couldn't believe it.
Although I was in the top stream right through school, if I wasn't interested in a lesson, I daydreamed. I regret now looking out of the bloody window, watching people playing football instead of concentrating on things like French. I keep telling my grandchildren that you have to go to school until the age of 16 and, while you're there, take what you're offered.
I was made a prefect and then a senior prefect, passed seven O-levels and went on to do chemistry, physics and maths at A-level, but I didn't complete them. I wanted to work and buy a car. For a year and a half, I worked for other people and then set up on my own. When I started out, I was a small-time trader. The only other person in my family in business was my Uncle John, who had a corner shop. I helped out and watched how he did things and very quickly I had a much bigger business than he had. Then I got into the electronics wholesale business and there was another person I looked up to and watched how he operated. And so on, through my career.
I've never had a mentor in the sense of someone I would go to for advice, but there have been a number of people I have admired, particularly Arnold Weinstock (founder of GEC) and Rupert Murdoch (with whom he was involved in the launch of Sky TV).
Entrepreneur Sir Alan Sugar was talking to Pamela Coleman
The story so far
1947 Born Hackney, north London
1952-58 Attends Northwold primary school then Joseph Priestley school (Brooke House comprehensive)
1968 Founds electronics group Amstrad
1985 Launches PCW8256 word processor, which sells for pound;300
1986 Sets up charity, the Sugar Foundation
1991-2001 Chairman of Tottenham Hotspur Football Club
1993 Founds Excalibur scholarship scheme for students from eastern Europe
1997 Amstrad split into Viglen and Betacom
1998 Honorary DSc from City University
2005 Appears in 12-part reality series, The Apprentice, on BBC2. Business empire estimated to be worth pound;700 million