Outside of North Norfolk, most pubs have more restricted 'permitted hours' but these might still be longer than their normal trading hours. So, for example, a pub which normally closes at 11.00pm might actually have permitted hours allowing it to serve until midnight or 1.00am. Once again, they can carry on serving after their normal closing time as long as they remain within permitted hours.
As far as trading outside of permitted hours is concerned, the law effectively remains the same as it was under the old legislation. It's illegal to supply alcohol, by retail sale, outside of permitted hours (except to resident guests in a hotel or inn). If the publican has won the lottery and wants to treat all of his customers, he can keep the pub open as long as he likes provided he gives away his products. However, as soon as he sells alcohol, he's breaking the law. It doesn't matter whether the alcohol was paid for in advance or whether it will be paid for the next day (and it certainly doesn't matter about the locks on the door or the positions of the curtains or the till). If the publican supplies alcohol outside of permitted hours, and the drinker pays for it (whether at the time, in advance or later), the publican is committing an offence.
Chris