Gordon Brown revealed he was once beaten with a belt by his headmaster for wanting to watch a Scotland football match during school hours.
The thrashing happened after Robert Adam, the headmaster of Kirkcaldy High School, discovered that some boys planned to sneak off to watch Scotland play Italy in a 1966 World Cup qualifying match on television, the Mail on Sunday reported.
Mr Brown confessed to being given the belt in a television interview with Amstrad boss and star of BBC1's The Apprentice, Sir Alan Sugar.
He said Mr Adam called the boys in to his office and hit them with his belt, a once widely-used alternative to the cane before corporal punishment was banned in schools.
In the interview Sir Alan asked Mr Brown: "When you were at school, did you ever get the cane?" Mr Brown replied: "The belt, yes.
Sir Alan then asked: "The belt? You got the belt?" to which Mr Brown added: "The belts were actually manufactured in my constituency."
According to the newspaper, the belt would have been a Lochgelly Tawse - a piece of leather with one end split into tails - which was manufactured in the Fife town of Lochgelly and widely used in Scottish schools at the time.
A friend of the Prime Minister told the paper the incident happened in December 1965 when Mr Brown was 14.
He said: "Scotland were playing Italy in Naples on a Tuesday afternoon to decide who would go forward to the 1966 World Cup.
"The headmaster announced at assembly that he'd heard some of the boys were planning to sneak off for the afternoon to watch the game on television and that would not be tolerated. But he said if there were any boys who were desperate to watch the game, they should come to his office after assembly to discuss it.
"Some of the boys went round, thinking the headmaster might put a TV in one of the classrooms. Instead, he got them in one by one, gave them a good belting, and told them if they tried to play truant that afternoon, they'd get another belting every day for a month.
"Scotland were beaten 3-0, so they didn't miss much."
Last year, Mr Brown recruited Sir Alan to advise him on business.