I think it's important here to distinguish between American bacon and English bacon. The bacon Americans have for breakfast and put on a BLT is what in the UK is called streaky bacon - much higher ratio of fat to meat. Plus it's sliced more thinly in America, so the only way to cook it, really, is crisply. That's why all this talk of non-crispy bacon in a butty is making the Americans gag - who wants a strip of flaccid fat?

The bacon used at breakfast and for a butty in the UK is usually back bacon - mostly meat, with a bit of fat along the edge. It's about two or three times thicker than American bacon - my (American) mother always says "I love that ham you have with your breakfast over there..." Many people don't fry their bacon in the UK, they grill it (that's broiling to the American contingent). So getting back bacon to be crisp takes a fair bit of cooking, and would make it pretty dry.

Oh, the other big difference is that pretty much all the bacon you get in supermarkets and diners and such in America is smoked. In England, you have a choice. A lot of people seem to prefer unsmoked bacon on a butty - for me, it's smoked every time.

There endeth the lesson.