Now this one’s a trick question because the answer is ANYTHING red and green, garish, that lights up or has any trace of glitter, snow or anything remotely festive (including Fair Isle patterns) is considered a ‘good Christmas jumper’. Whether you snap yours up from a store or go full DIY mode and make your own (yes, sewing tinsel to a knitted jumper counts) — the best Christmas jumpers are known for being over-the-top and, frankly, pretty ugly. So just have fun with it!