Having had another look I think that the initial contact was shoulder to shoulder and then O'Brien's head hit Scruton's shoulder as opposed to Scruton's shoulder hitting the head (if that makes any sense!).

Does it? Are you sure?

Absolutely conviced and certain. Bugger, I need to draw a new line.
__________________________________________________________________________

Ah, but as has been pointed out, as Nicks shoulder can be in 2 places at once, it can be both above and below your line at the same time. Quantum! and stuff.....

You really need to draw some sort of sphere rather than a line.