That's not how concussions work.
Part of the problem is that the English don't in General have the same understanding of how serious concussions are. In America, we have American football where the players are supposed to just violently hit each other, so there have been a lot more studies on concussions and more protocols put into place.
I'm not English. We have Aussie Rules Football here and concussions have become a serious issue over the past couple of years. So I know it's quite dangerous to play on after getting hit.