One of the interesting parts of having been involved in a short act of violence is that it plays through your mind for days and weeks afterwards. The same is true of Henry who has to go from his encounter with the muggers straight into a squash game. His mind is elsewhere and it takes him time not just to settle but get rid of the aggression that flows through his system.
Where McEwan gets it right is in the way he manages to get a 40 something character with more money and medical knowledge than certainly ninety off per cent of the readers and yet make his feelings something that can easily be identified. That must be the gamble of setting it so definitely in a known context. Just as he describes the various unknown reactions to the Iraq war no doubt there was a hidden reference there to the inevitability that some readers will by this point have sided firmly with Henry or as the third chapter begins will have decided they can’t stand him. I still like him but we’ll see if that continues.