Still does, I think. Sold up his sports shops (£4.4 million?) and moved to the Caymans. Bill and his wife, Judith, have been involved with a charity, Coaches Across Continents, run by their son, Nick.That generation had miss-shapen 'caseys' to practise with as kids. Plastic footballs came in about 1965 iirc, so there should be a marked difference at some point. Alan Peacock was a prolific header of the ball, but shows no ill-effects. It's not straightforward.
In one of those Man U cup-ties, Bill Gates had his jaw broken by a blow from Brian Kidd. Things like that, clashes of heads, being hit in a 'wall' point blank etc could maybe do more harm than many free headers.
Sad to hear about Bill Gates. Remember him living a couple of streets away. I was wondering the other day, did he actually live in the Caymans?