Mr Red, I'm wondering if the lad at your boarding school was playing a record called 'Tom Hark' by 'Elias and his Zig-Zag Jive Flutes? It's a South African piece, and features lots of tin whistles and a guitar.
It was always being played on the radio in the 1950's, and was the title music to The Killing Stones (a TV series)
I've just found it (after all these years!) on Youtube. (Dabs eyes with hankie)

Paul Simon mentioned in the programme that he loved the 'tin whistle bands' which were found all over the townships.

'Tom Hark' has always seemed to me to evoke Africa. Elias and his mates speak a bit before the music starts. But it isn't in Zulu. It could be Ndebele or Pedi.