Living in England: What is a bacon buttie?

It used to puzzzle me, not so much the bacon but the 'buttie', or 'butty' as it is more often spelled. The Oxford Dictionary says it is a sandwich that derives from 'butter', and the word seems to be used only for hot fillings. So the sandwich filling of a bacon buttie is bacon, but what is the bread called? Up Durham way: a 'bap', of course, or a 'stottie/stotty'. Baps are soft like hamburger buns but they can grow very big, like 6" across; stotties are more dense and heavy, made as 12" cakes. Tremendous differences across England in naming these kinds of bread, though.

Bacon at St Lawrence market, Toronto
streaky bacon on left, peameal slices in
middle, peameal bacon loaves on right

So, a bacon buttie is a bacon sandwich. The filling? Bacon – what Americans would call 'Canadian bacon' (made from pork loin), more solid than normal bacon which the English call 'streaky bacon' (made from pork belly) and the Canadians call 'side bacon'. The Canadians themselves have 'peameal bacon', so named because the log of pork loin meat is rolled in ground dried peas; when sliced, the bacon pieces have a rim or crust of peameal. Because of its excellent preservative qualities, this kind of bacon was apparently the biggest Canadian contribution to England during the war; it was called 'lorry' or 'boot' bacon because of its transportability.
I learned all this from our trip to Toronto recently where we ate peameal bacon sandwiches at the St. Lawrence market (highly recommended to us). And upon returning to England, I decided it was high time I tried a bacon buttie, which I had been avoiding all these years. Rather than being disgusting (because all there is is bacon, butter and bread), it was actually very very tasty, probably due to the six kinds of umami in bacon which are thought to be addictive (see the Wikipedia article on 'bacon' – very informative!). Apparently bacon sandwiches were a favourite food of Fergie (the Duchess, not the footballer) before she went on her various diets. And they are ubiquitous in England – many people eat these for breakfast on the run.
So how do bacon butties compare with peameal bacon sandwiches, and BLTs for that matter? Though sparsely appointed, a bacon buttie goes down very smoothly, while I struggled to finish even one half of my peameal bacon sandwich (had to take the other half away) because it was so stuffed with 8 layers of bacon. I presume the peameal bacon and BLT (bacon, lettuce and tomato) sandwiches are better for your health because they at least have some vegies in them, and the latter can be made with wholemeal bread. But I must say, that bacon buttie was sure tasty, probably because it was hot bacon and had more fat in it than the cold peameal bacon sammie. (The British Sandwich Association gives an annual Sammie Award; maybe I should nominate the bacon buttie.) Now converted, I'll have to try not to make them a habit. Maybe a 'chip butty' is next.