British bacon is a bit like a combination of American and Canadian (though obviously Canadian bacon evolved from the British style and not the other way around). With British bacon, you take the loin but leave lots of lovely fat on it, especially the fat cap, and include the part where the loin attaches to the same cut American-style is made from: the belly. So a full rack of British bacon is the pork loin with plenty of pork belly attached to it: the loin section is the rasher (what [this glossary of British food terms] calls "a thin, floppy slice of fatty ham") and the belly is the streaky. Then you take your pick.