It was 1971 and 21 SQ (VIP Transport) was practising for the South African Republic 10th Anniversary flypast.
It's a complex story but as they were running late, the lead was asked to speed up and they entered cloud. The pre-calculated turn radius was incorrect and with the (significantly) higher speed, the formation impacted Devils Peak, just above the Rhodes Memorial. All aircraft hit the peak, and all aboard perished.
Apart from the significant human tragedy, the accident impacted the SAAF severely as the aircraft were irreplacable - South Africa was being sanctioned for it's Apartheid policies - and it was some years before the aircraft were replaced, through a deal that cost the labour party in the UK dearly.
...The complex webs we weave...