Excitement is building in the run up to Christmas and shoppers at Marks & Spencer have been wowed by the store’s new £12 product set to fly off the shelves. M&S is famous for its unique and delicious festive food and drink, from "Percymas" mince pies to luxurious, sparkly gin liqueur with edible gold leaf.This year the high street chain has pulled out all the stops with what could be its most popular product yet.