My father, Syd Hoare, who has died aged 78, was an Olympic judo competitor, author and commentator.

The son of Alfred Hoare, an executive officer at the Ministry of Defence, and Petrone (nee Gerveliute), a waitress, Syd enjoyed a wild childhood in postwar London: scrumping, climbing trees, jumping out of bombed-out houses on to piles of sand and being chased by park keepers. At 14, while a pupil at Alperton secondary modern school, Wembley, he wandered into WH Smith and found a book on jujitsu, which led to judo lessons at the Budokwai club in Kensington and sparked a lifelong passion for the sport.

Syd quickly became obsessed with judo and underwent intense training, often running the seven miles back to his home in Wembley to lift weights after a two-hour session at the Budokwai. In 1955, at 16 he was the youngest Briton to obtain a black belt and two years later won a place in the British judo team. He respected not only judo’s physical and mental aspects but its link to eastern philosophy.

After a frustrating stint doing national service in the army, he lived for four years in Japan, training at the Kodokan dojo in Tokyo and immersing himself in the country’s culture. He became fluent in Japanese and later gained an honours degree in Japanese language, literature and history at the School of Oriental and African Studies in London.

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Syd was a member of the first British judo team to compete in the Olympics in 1964 and was a silver medallist in the European Championships in 1965. On retiring from competition he was appointed chief instructor at the Budokwai and later became national coach and chairman of the British Judo Association. He was awarded 8th dan in judo and 5th dan in sumo.

Raising awareness of the sport of sumo in the UK, he founded the British Sumo Association and created the first British sumo team, who competed in the World Championships in 1992. This led to appearances on TV shows including the Jonathan Ross Show and Matthew Kelly’s You Bet, usually tying a mawashi – sumo belt – on to the presenter. Trading on his “tough guy” looks, he played small film roles in films including Guy Ritchie’s comedy crime caper Snatch, the sumo wrestling movie Secret Society (both 2000) and Kenneth Branagh’s As You Like It (2006).

Syd wrote many articles and books on judo, other martial arts and keep fit, including the bestselling A-Z of Judo (1993). He self-published A History of Judo (2009) and A Slow Boat to Yokohama: A Judo Odyssey (2010), about this judo career. He also commentated on judo, sumo, Taekwondo and wrestling, for Eurosport.

A judo traditionalist who cared deeply about the roots of the sport and how it was maintained and developed, Syd was brusque and unconventional but patient and fair with a mischievous sense of humour.

He is survived by his wife Oksana Khoutornaja, whom he married in 2002, and their children, Viviana and Rafferty, and by Jocelyn, Zoe, Max and me, the children of his marriage in 1973 to Sophy Fox, which ended in divorce.