Grace rushes over to Kreshnik, and starts speaking hurriedly to the cashier. "Sorry! He's, ah, new here. Also the world is ending so I would go find your family and get somewhere safe. Have a nice day!"
She drags the vampire away and says "For an ancient vampire, that was rather stupid. Also give me that."
She swipes the money out of Kreshnik's hand, stuff it in her pocket, pulls out a £20 banknote and puts it in his hand.