Some hard headed economic calculations lie behind an emotive row over whether or not supermarkets should be made to close early on Sundays. In public, the argument over Sunday trading goes back and forth over ground that we can all understand and on which we can hold opinions – such as whether a customer's right to shop when and where he or she chooses matters more than religious or social objections that it is restful to have one day in the week when the frantic pace of commerce slows and people – including staff who work in supermarkets – can spend time their families.
As you would expect, the churches and the shop workers' union, Usdaw, are prominent advocates of keeping Sunday special, while the supermarket chain Asda is a powerful voice in favour of customer choice.
What might come as more of a surprise is that there are prominent people in the retail trade who do not want Sunday trading restrictions to be abolished. They include Justin King, the chief executive of Sainsbury's, who has warned that "a great British compromise is in danger of being lost".
Sunday trading will be one of the first issues in David Cameron's in-tray when he returns from his holiday in Majorca this Thursday. It is a political hot potato that could cause yet more trouble between the Conservatives, who favour unrestricted Sunday trading, and their Liberal Democrat partners, who oppose it.
The Prime Minister is likely to be fairly neutral on emotional questions about whether Sunday is a special day, and to focus on the economics. The country is in recession, supermarkets have been hit by competition from the internet, and the Communities Secretary, Eric Pickles, has hinted that he is receptive to the argument that longer supermarket opening hours means more cash in the tills. The question is whether the supposed extra trade will be worth the social costs – and that cannot be answered, because no one has any reliable data.
Before restrictions were temporarily lifted for the Olympics, the law restricted the major shops in England and Wales to six hours' trade on a Sunday, which most interpreted as meaning from 10am to 4 pm or 11am to 5pm. Shops with a floor space of less than 3,000 sq ft can stay open longer. Since the temporary relaxation came into force on 22 July, five Asda stores near the Olympic Park have been open 24 hours on a Sunday. Asda's other London stores have stayed open until 10pm, stores outside the capital until 8pm. Asda has been giving ministers "regular feedback" on what the customers think of this change, which they say has "become more popular as time moved on". But they cannot translate that into hard figures. An Asda spokesman said it is "too early" to put a figure on how much extra business has been generated.
"Our customers like the convenience of us being open longer, as it means they can shop when it suits them, not when it suits us," he said.
The Labour Party is focused on the potential impact on the family lives of supermarket staff. "Sunday is a day which families can spend together and this should not be threatened by supermarket shop workers being pressured into working longer hours," said shadow planning minister, Roberta Blackman-Wood. "Longer hours for customers would also create longer working Sundays for their staff."
But just as the shops cannot say how much extra business Sunday trading has generated, the unions cannot offer anything more than "anecdotal evidence" that supermarket staff have been coerced into Sunday working.
The economic benefits do remain uncertain. Victoria Redwood, the chief UK economist at Capital Economics, believes that the overall impact of permanently extended Sunday trading "might not be very large". She said: "It would probably just prompt consumers to alter when they shop, rather than how much they buy. Larger retailers, including department stores and supermarkets, would stand to gain most, as they are currently most affected by the restrictions. Small independent stores would lose out."
Without hard facts, the argument rumbles on.
The shopper: I'd prefer to shop on a Sunday, when I'm relaxed
Francesca Giorgi Monfort, 22, is a student in London who works part time for a shoe company as a marketing assistant
Working and studying makes it hard to go shopping during the week, and when you go out to do your weekly shop on a Saturday it's very busy and crowded. The supermarkets are always packed. I'd much prefer to do it on a Sunday, when I'm relaxed. After a whole day of work I just want to go home and rest.
So I am totally in favour of extending trading hours on Sundays. There have been arguments about making staff work on a Sunday – but no one is forcing businesses and their staff to do anything. It could even help people to get jobs, or give young people a chance to make some money at the weekend.
If shops were to open on Sundays, I don't necessarily think there would be a lot more customers to begin with, but they would spend more money. If you take your time around the store, you end up buying more things.
The shopkeeper: We currently have a decent compromise
Nigel Dowdney, from West Earlham, Norwich, owner of the Earlham Shopper
I feel there is no need to change. Extending opening hours leads only to people spending their spare money over a longer period, with no boost for the economy. Sales have flatlined. Compared with last year, Sundays have seen a fall. We are also in the middle of a recession so people are more careful with their money and no longer tend to look at premium goods but value goods instead. We currently have a decent compromise which should be maintained.
The cafe owner: Shops shouldn't be held back by traditional rules
Rob Lloyd, 25, runs an independent coffee shop in Leeds
I'd love for our shop to be open an extra day every week. We would love to do that for our customers, if I could pay the staff. I'm aware that some religious organisations have claimed that the Sabbath should be kept holy, but we're no longer a society with a singular Christian religion. We need to bring ourselves up to date. Shops shouldn't be held back by traditional rules. I work long hours in my coffee shop from Monday to Saturday. Sometimes we'll open at 8am and close at 7pm. So unless I can get things from the cash-and-carry, the only day I can do the weekly shop is Sunday.
The vicar: Longer opening hours would affect churches
Reverend Rhiannon Jones, 39, Transforming Church co-ordinator for Birmingham Diocese
Extended trading on Sundays diminishes the special character of Sundays and the opportunities to invest in one's family, community and spiritual life. Lengthening opening hours of shops would impact on churches. Another major factor is the wider impact on society of Sunday trading and losing the benefits of a slower pace of life and increased time with family. Increased consumer choice and flexibility always comes at a cost and is often paid by the poorest members of society, who feel obliged to work on Sundays. It may look like a social benefit but is really a wolf in sheep's clothing.
Interviews by Charlie Cooper, Liam O'Brien and Davina Cameron-GaleReuse content