I first went to America in 1985, and the most haunting thing about my visit was queueing in the bar at Heathrow some time before the flight departure. For some reason there was a problem behind the bar, and the (black) barman had disappeared to sort it out. The man in front of me turned round, then looked at me and said, in an American accent: 'He's probably gone to climb up a tree.'
It wasn't just what he said that I found deeply offensive, but also the fact that this man should assume that I shared his views.
Fortunately the world has moved on a great deal since then, and last night is a major indication of that move.