I have a couple of these 1961, 1967 via download from Duke, plus a vinyl of the 1979 Classic and Senior Races, originally produced by a radio and TV shop in Douglas, sound effects aren't so good on that, but the commentary has the atmosphere. I did a pirate tape from a friends vinyl of 1961 and the 62 Junior, but that has become knitting wool through overuse.
Good Luck in contacting Manx Radio, but don't hold your breath