they cannot legally prevent you from leaving the ground at any time, they can enforce egress routes that mean you go nowhere near the North stand, even then they are on dodgy ground, it's archaic in the extreme.

What's next, will they be throwing carrot sticks into the crowd to help us with our "five a day"?

Now there is an

Club or stewards can't do it.

Police can though if they feel there is credible threat to the peace. Anybody thats been in London during May Day or to Nottingham Carnival knows that first hand.

That said, would be really surprised if they did it.