According to a BBC investigation, shoppers are being charged more for buying from big-chain convenience stores. In one case, a trolley of groceries cost almost £10 more in a smaller shop than at the company's superstore.
The BBC looked at a mix of own-brand and branded items from two types of Tesco, Sainsbury's, Marks and Spencer and Waitrose. The supermarkets said the price difference was due to the higher costs of running the smaller branches.
At Marks and Spencer the same trolley of shopping cost £103.26 at the Birmingham High Street store and £112.44 at Simply Food in Birmingham New Street Station.
In the Tesco superstore on Camden Street, Birmingham, a banana cost 9p, but was priced at 25p at the Tesco Express in Fredrick Street.
With normal economy and supplier demand, it is often the case that smaller shops, and those in more remote areas, will charge more.
When you look at service station petrol prices on motorways, that is very telling, because they are normally hugely more expensive but they are open 24 hours and have higher overheads.
With smaller stores, deliveries are also harder to get to them. It is something which has always happened and something that will always happen in future.
Nevertheless, the Price Marking Order 2004 orders that the price must be clear, consumers should never have to ask the price of anything and it should be clearly available without having to ask, which supermarkets are largely very good at.