The Webb Ellis story is a myth. From the Encyclopaedia of Rugby
"Not only did a schoolboy contemporary of Webb Ellis refute the notion a few years later, but there is also the fact that rugby was by no means the first code to involve running and handling. In fact, before Webb Ellis did his party trick in 1823, all codes of football involved running and handling."
The boys at Rugby school apparently were constantly revising the rules.
It seems shouting "my ball, MY ball!! It's MINE!!!" before picking up the ball, refusing to give it back then running away was a feature of the game that appealed to our future political leaders.