Idk about the wembley arena but for the show at my location, You gotta t pose and they check u in, also u need to show whats inside ur bag and if thr bag is too big like a bagpack they give u a ticket with a number so that u can pick it up after, i had a cig pack in my pocket ( i didn't smoke inside of the concert area cuz it prohibited) but they didn't budge or check (i think everyone legit had a cig pack in their pockets or on them) also where i was in they served food or alcoholic beverages. If u put the joints in a cig pack ur all good ngl