No-one's got that Shankly quote right, but I won't dwell. Instead, and more apropos, is this one of his: "If a player is not interfering with play or seeking to gain an advantage, then he should be."

The offside rule is excellent and the game would be intolerably dull without it. The challenge is to apply it well. Apart from the issue alluded to above, the assistant ref has to be looking at two things at once, the position of the receiving player and the ball at the instant it's passed to that player. Not only that, it's impossible for the assistant ref to maintain a parallel line of sight at all times. You're always going to have these marginal issues in sport (look at LBWs and caught-behinds in cricket and how even sophisticated technology struggles with them) and the spirit of the thing must always be to accept that occasional wrong calls will be made and you put up with it in a sporting manner.