For half a century he was the voice of rugby, renowned for predicting dancing in the hometown streets of winning teams.

But rugby commentary was Bill McLaren’s second career: between matches, he had a day job teaching PE in the schools of Hawick, in the Scottish borders.

William McLaren was born in Hawick in 1923. From an early age, a succession of teachers had to threaten to bar him from rugby practice in order to persuade him to do his homework.

He had just made Hawick’s first XV when the Second World War broke out. He subsequently enlisted as a spotter with the Royal Artillery, serving in the Battle of Monte Cassino.

Having witnessed the death of close comrades, Mr McLaren returned to Scotland with a sense that he had to make a difference, to create a better world for future generations. It took another brush with death, however, for this inchoate desire to become reality.

In 1947, shortly after he had trials for the Scottish rugby team, Mr McLaren contracted tuberculosis: a life-threatening condition at the time. For 19 months, he was confined to an Edinburgh sanatorium.

In the depths of the disease, it was only regular visits from his wife Bette that kept him going. “I told her not to bother with me any more, and to find herself a proper man,” Mr McLaren later recalled. “She just ignored me - bit of a trend that, by the way.”

Eventually, he did recover. But illness had destroyed his rugby dreams. Into the vacuum, however, flowed a renewed desire to help create a better post-war world. So he enrolled on a teacher-training course at Woolmanhill College, Aberdeen.

After graduation, he became an itinerant PE teacher, working in four Hawick primaries. And, from 1959, he worked three afternoons a week at Hawick high school, coaching rugby, athletics and cricket.

For Mr McLaren, taking part was never the point. The point was competition. The point was winning. He quickly established inter-school rugby and athletics tournaments among Hawick’s schools, something previously unheard of at primary level.

He wanted all children to achieve their best, regardless of ability. One girl, for example, struggled to clear the gymnastics vaulting horse. Eventually, Mr McLaren picked her up and threw her over the horse. “You did it!” he told her triumphantly; her confidence with the equipment grew as a result.

For more talented pupils, however, he was unyielding in his drive for excellence: they would have been expected to vault over the horse like Olympic gymnasts. He was renowned as a harsh disciplinarian, and was not above wielding the belt when he felt occasion required.

It was no coincidence that his coaching career produced a series of Scottish international players, including Jim Renwick, Colin Deans and Tony Stanger.

Early on in his career, Mr McLaren had discovered that he could combine teaching with a media career. He began as a match reporter for the Hawick Express, progressing onto BBC local radio. By 1953, he was covering Five Nations matches for network radio; a television post followed in 1959.

A natural perfectionist, he would compile handwritten spreadsheets, meticulously detailing the names, ages, weights and backgrounds of everyone involved in a match, down to groundsmen and referees. This, too, was a lesson for his pupils: knowledge and achievement, he told them, came only from meticulous study and preparation.

As a commentator, he was renowned for his improvised quips: “that wee ball’s gone so high there’ll be snow on it when it comes down”, “he’s like a demented ferret up a wee drainpipe” and, most famously, “they’ll be dancing in the streets of (the winning team) tonight”.

Such one-liners also won him classroom support: “so you’re a hooker, then?” he greeted a young Colin Deans at their first meeting. This eventually became the title of Mr Deans’ autobiography.

Mr McLaren retired from teaching in 1989, and from commentating in 2002. But he remained intensely loyal to Hawick and its schools: in 2006, he provided the voiceover for Hawick High’s application for School of Ambition status.

Bill McLaren died on January 19, aged 86. Among his surviving family are two Scotland scrum-halves and a fullback.