Airways used to serve MAN. If memory holds up, it was an extension of the FRA service? JNB/FRA/MAN arriving around mid-morning? Then departing late afternoon for the same route. This was closed more then ten years ago (I think).
I agree that MAN should be a good bet, however, the ex-South Africa residents are predominantly in the South East, I should say.
Nationwide will be irritated as it spikes the guns of their March 04(?) start of JNB/LGW on the 767 all Y config.