My friend was refused service by M&S when buying alcohol but had a fully valid drivers license Can they do it?

He had a completely valid drivers license, with the monogram on it and all. He's 20, gave a bottle of brandy to the woman in the checkout, she looked at his ID and pressed the bell, the manager came, and they were being morons, saying his photo looks like it was put in or something (basically they said it was a fake) he had his student ID, debit card everything, they refused him service. Looking at his drivers license theres nothing wrong with it at all, these people are brain dead, it had the monograms on the photo and he always uses it to buy alcohol or as general photo ID.. I find it funny how he could withdraw like 10k from his bank if he wanted to with it, but it's not good enough for M&S and their anti-terror top security ID checks. What should he of done? Could he sue them?