I'll give you the fact he was talking about black immigration from the West Indies, but on the general principle of mass immigration into this country and the overall trend, he was spot on. Bloodshed, the increasing normalisation of alien culture, colonisation by stealth (first locally and increasingly nationally) and population replacement - it's all happening.
The trend for non-white, non-European immigration into this country is relentlessly upwards and the birthrates of those non-white, non-European immigrants massively exceeds that of the native population. How else do you imagine that trend can end but in the scenario Powell described?
It doesn't suit you to acknowledge the seismic changes that are taking place, but that doesn't make them any less real.