You probably have not heard it by that name. 'Butty' is a term the English use for sandwich. Seems the new prime minister, David Cameron is a fan of bacon butties. Daniel Craig, (James Bond), demands them on the set when he is filming and has them flown in from England.
According to a scientific study (True), an integral part of a successful bacon butty is the aural factor - how loud the crunch is when you bite into it. A classic bacon butty is soft white bread, butter, bacon fat, crispy streaky bacon. Other names are bacon bap, bacon sanger, and bacon sarnies. Ah, by any other name - Yumm!