To make a long story short, I only recently learnt that Morrisons policy is that their online prices can be different from their in-store prices. So if you see a price on Trolley for a product at Morrisons it is for online shopping. If you go to the store it probably will be different (i.e. more expensive). Morrisons say the only way to find out the in-store price is to go to a store. No other supermarket, to my knowledge, does this.