Shops over a certain floorspace have restricted opening hours on Sundays. (see: https://www.gov.uk/trading-hours-for-retailers-the-law https://www.gov.uk/tradin

Shops over a certain floorspace have restricted opening hours on Sundays. (see: https://www.gov.uk/trading-hours-for-retailers-the-law https://www.gov.uk/trading-hours-for-retailers-the-law) Some shops exploit a loophole in that a shop isn't open unless the tills are open. If you are doing your big periodic grocery shopping in a large supermarket, then it may take you an hour to get everything into your trolley and round to the tills. So, a shop that is legally open from 1000 to 1800 can open to shoppers at 0900, because few customers would actually buy anything in the first hour of opening anyway.