I find it disappointing, but not surprising, to see that the rail industry seems to operate as if it were somehow exempt from, or incompatible with, the same methods and hours of working (including Sundays) which work absolutely fine in other industries where Sunday is a working day - such as retail, airlines, cruise lines, customer services, the emergency services and so on.
If the industry wants to become more customer centred then they must adopt more modern working practices, like forcing people to work on Sundays. If this means that people who've had it "good" until now - by not having to work on Sundays for example - have to be made redundant because they won't accept more realistic working hours/days, then so be it.
In my view, it is frankly unrealistic to expect not to have to work on any given day of the week if you work in an industry that operates 7 days a week. It doesn't mean that you have to work more hours a week - but it does mean you have to be more flexible about what days you might be expected to work. If I applied to work for the rail industry - or any other 7 day industry - then I would reasonably expect to work any day of the week. If that doesn't suit you, choose another industry which works 5 days a week.