It's only 50p but I'm intrigued to know if it was genuine or not. We're in London for a few days, waiting to get into an attractive. DS is hungry and I'm thirsty so we go to one of those little individual stalls, cash only. It comes to £9.50. I give her a £10. She only has £1 coins, can't give me any change. Fine, I say keep the change. DH says its a con and if they took an extra 50p off everyone needing change through the day that would really add up.