With less than a week to go before millions of hungry people tuck into their Christmas dinners, the team reveal various surprises behind festive food. Jimmy Doherty heads to Sri Lanka to find out if there is anything in yuletide spices that can give a person a dose of Christmas cheer. Matt Tebbutt visits a mince pie factory to learn the difference between raisins and currants. Helen Lawal investigates how well sprouts should be cleaned and Kate Quilton checks out a more decadent festive roast from the past.