A little column A, a little column B?
The French brands have done a fantastic job of marketing their saddles and creating an effective sales model, no doubt about that.
They also do a good job of installing human creature comforts in their saddles in terms of human fit- length and width of working center, twist wider or narrower, stirrup bar placement, lots of options about flap configuration. I’m going to generalize wildly here by saying that British brands, like Black Country and County, often do not have the same range of options, especially in seat depth/breadth and position of working center. If you are comfortable in the saddle, this is not a problem for you. If it doesn’t suit your conformation, they may not have another model in their range that does. (Another poster here once remarked to me in rather hilarious fashion “it sounds like your derriere is of the French persuasion” because I’ve never had great luck finding a British-built saddle that I found comfortable, although I’ve tried! That’s just about my conformation.) The French saddles also have a certain “look”- they’re available in beautiful leather, they have trim options, etc.- whereas the British ones are crafted more to be workmanlike than aesthetic. However, that stout thick grain leather wears like iron and will last you forever. They’re good quality saddles. I also don’t know of a British saddle made in such a way that it must go back to the manufacturer for repair, whereas there are elements on some CWD saddles, for instance, that are designed not to be reparable by your average saddler.
If you aren’t able to find the fit for your own derriere in Black Country, other British brands that can do wide flat pony back with some more options for the human conformation might be Frank Baines and Harry Dabbs.