If you want a special bird on your table this Christmas, why not have a large sutton Hoo chicken? These birds are extra mature & slow grown (16 weeks), specially for Christmas and are great value at £6.79 / kg. (They are usually £8 / kg, but sadly an Islington restaurant they supply, Le Coq, is closing this month and so they have big chickens filling up the hen-houses - so help them out...!)
Alternatively, turkey legs are always a very canny buy - bags of flavour, sold at a knock down price (because people by the Crowns for Christmas), they can be huge (1kg plus), and freeze very well.