Though the concept of sausage wrapped in pastry exists in every cuisine in one way or another, the British have claimed sausage rolls as their own. They are always welcome, especially at holiday time. Boxing Day, a national holiday in Britain, celebrates the traditional post-Christmas servants’ day off, when upper-class families were forced to fend for themselves and subsist for a day on a lavish buffet of leftover feasts from the week. Sausage rolls are often part of the spread. A…