We thought it might be Lionel Bringuier, who’s come out on a DVD made when he was 24.
Other authorities suggested Roberto Benzi, but we have not been able to trace the date of his first recording. He began working with Philips aged 23 in 1960.
The closest we have come to a definitive junior champion on record is…. (drum roll) … Mikko Franck, the Finnish conductor who recorded Sibelius for Ondine in 2000, at the tender age of 20. Beat that.