Hey - don't tease me, I'm getting worried!
Anyway, I've been having a long, hard think and, you know what? I think you may actually have a point over the penalty 'offside/onside' incident (albeit I suspect you don't know why).
I'll leave you to have one more go at explaining why it was offside and then I'll give you my explanation.
EDIT: Forget that, just checked on what I was thinking about and it doesn't give you any help, Peter.
The law change that said you were only offside if you were 'interfering with play or seeking to gain an advantage' pre-dates this penalty - it stipulates that you are not offside merely by being in a technically offside position. (I'd thought that may have come in after this pen).
So nerr!!