I still agree that no one should be forced to work on a Sunday (or indeed on a Friday or Saturday, if that is their religion's prescribed day of rest), but a lot of shops now have weekend staff who are not the same people who work during the week. Like kids (over 16) who are at school in the week and work one day to earn an allowance, or part-timers who work a couple of evenings in the week and all day at weekends. Plus, we have strict laws from the EU about working hours - in most industries, everyone must have by law at least one day per week off work. Working on Sunday is usually voluntary, employees get a day off in the week in lieu, and in some circumstances, people who work Sundays get paid at time-and-a-half. So I'm not sure the potential for staff to be abused is a valid argument anymore.
Trying to pretend that Britain is still a Christian culture is ridiculous. It may be true that the majority of people would give their religion as "C of E", but I'm sure a lot of those are actually what Richard calls "devout don't cares" - people who vaguely believe in a God, but don't really follow any religion in particular. People who are Christian by default - simply because they were taught the religion as children, and haven't found another one they like better (or haven't bothered to look). Keeping Sunday special might have worked in the 1980s, but it doesn't seem true now. So when is anyone going to have the guts to tackle this in Parliament?