chip butties (a mainly northern tradition; even if you call it a chip sandwich rather than a butty, it is about as working class as food can get).
It depends where you think 'northern' is! Londoners think it starts at Watford, Midlanders have a fine tradition of chip butties or sarnies....go to football or rugby matches and everyone eats them....of all classes....male & female. I'm sure there will be something about sport and class somewhere in this book but some of the poshest people I knowgo to matches.... especially rugby....union or league!