Regrettably I only arrived at Farnborough after most of the 'interesting' test flying had moved to Bedford. I was told that a 'supersonic' overland corridor still existed along the Bedford Levels where TPs could produce an overland bang (it was still in their FOB anyway)
My one and I believe only experience of a 'boom' was in the mid/late '60s when they were evaluating the effects of them over land prior to Concorde's first flight. I was at my parent's home in Chesham, Bucks when with a clear sky in the middle of summer, I heard what I thought was thunder. A few days later, I met Honey Monster, (we were in the same ATC Squadron) and he said did I hear the boom the other day. (Honey Monster by the way, was posted to Farnborough a few years before me.) Anyway he told me it was Farnborough's Lightning, which had been detailed to lay down a boom from Reading towards central London.