Viola! 
American biscuits (and sometimes scones) fall under the “shortened” category.
I’ve previously shared the story here of my friends who immigrated to the U.S. from ireland. Soon after they arrived here, they were in a breakfast restaurant, and saw “biscuits and gravy” on the menu. The only thing that they could picture was cookies topped with brown beef gravy – they were pretty sure that that wasn’t what the dish was, but they couldn’t imagine what it acutally was, so they felt compelled to order it, just to figure it out.
Actually, if you want sausage gravy, you pretty much have to make the sausage from scratch. American breakfast sausage, which is what you use to make the gravy, is nothing like any type of sausage I’ve encountered in the UK (or elsewhere in Europe, for that matter).
The plus is, though, you don’t have to stuff it or anything. Just throw some ground fatty pork with some sage, black pepper, and salt and you’re pretty good to go. (Often you’d also add a little nutmeg or clove, some brown sugar, and some hot pepper flakes, and even other herbs like thyme, but those are your two basic ingredients to give it that American “breakfast sausage” flavor.) There are English sausages with similar flavorings, but most of the British style sausages I’ve had that I remember have breadcrumbs or some kind of stretcher in them, which gives it a different texture.
When I make it, I sometimes use maple syrup instead of brown sugar. I was shopping at Walmart last week and found maple sugar was for sale. I’ll have to give that a try sometime.
Maple Leaf makes a decent bulk breakfast sausage, but it’s just not as good as Jimmy Dean’s. 
When I was living full time in Moscow, I also tried making British bangers from scratch. The recipe called for lots and lots of breadcrumbs, and they never came out quite the same as the real thing. I had to substitute imported Weisswurtzel instead. 
Is Bisquick or some equivalent product sold in the UK? To make American biscuits, all you have to do is add milk (and/or buttermilk), knead, and bake.
Absolutely. The same family - enough to see a resemblance - but certainly not twins. Possibly not siblings. I bake a lot too, and I make both (though I tend to make biscuits more often than scones these days); I find scones are a useful basis for comparison when explaining biscuits to Brits, rather than starting from scratch or reciting a recipe.
Yep. Well, a few others here appear to disagree, but I am, and it’s not from my time spent across the pond.
Even without Bisquick, you can make delicious biscuits with just self-rising flour and cream, as demonstrated here. That’s not the usual method for biscuits —typically, butter and/or shortening is involved, and sometimes buttermilk — but even if you don’t have self-rising flour, all that is is flour with the baking powder already in it, so you can still make it by just adding the appropriate amount of baking powder. I know the recipe sounds somewhat odd to someone who makes biscuits the traditional way, but it works great for me, though, like I said, I’m a Northener so my opinion of biscuits should be taken with a grain of salt. But you should believe in Kenji and Serious Eats.
Not really. You can get it, but it’s not as though you’d expect to find it easily in supermarkets: you’d need to get it from a specialist who sells American products (or from Amazon, obviously…)
They’re so easy to make that I’ve not investigated packet mixes…but that’s not to say my compatriots wouldn’t be so inclined. You can buy Yorkshire Pudding Mix here, for crying out loud.
When one makes one of those mixes, how many of the resulting Yorkshire Puddings are capable of posting on the SDMB? 
The brand name is familiar - although in my head it made me think of milkshake powder (I realise now that’s Nesquick)
Or indeed, frozen cooked Yorkshire Puddings. SACRILEGE!
Wait, you mean popovers? 
Basically…yes.
I know, I know. I’m kidding because of the scone vs biscuit discussion. I still think scones and biscuits are fairly closes iblings. I’m looking over various scone and biscuit recipes, and to me it clearly seems there’s a bit of an overlap at some points. Some scone recipes are just flour, butter, shortening, and milk/buttermilk, which is the same as some biscuit recipes. And, yes, I know you can get wildly different results using the same ingredients depending on method, but there’s a grey area where they intersect. The stuff I had in Scotland at the restaurant I worked at, I swear, I was not able to tell the difference from being a type of American biscuit.
'tis a fair point, I think. I’m being quite deferential about the difference because of how attached some may be to versions which are very distinct from each other…but I think of a biscuit as being, fundamentally, a very plain scone (because I knew scones first, so they’re my basis for comparison). Though contextually, they’re used very differently!
I don’t think that’s how I came to be. Got me a bit concerned now…
And we all remember that dreaded blancmange incident…