National Express check all bags you take onto the bus now, not sure when this started but any unopened drink gets put into the hold until you reach your destination
You absolutely cannot drink on National Express coaches any more, I suppose it will be completely down to the driver, but I've known 2 people in the past 12 months get thrown off national express coaches for drinking
Not sure when this came into force but the last one we used were treating it like you were visiting somebody in prison the last time we went on one