The grandson of a meat cutter, and former meat packer, let me say it one last time:
The method of preparation does NOT define the cut of meat... There are steaks for braising, roasting, grilling, frying, broiling, and stew. You want proof? Try grilling a flank steak and then try braising a strip steak, then try cooking them properly-- the flank by braising and the strip by grilling. You'll find the quality of each meat to be better when they are cooked properly.
Niel you can go try this yourself, but I believe that the British butchers use a different method of cutting than the American map-- however it shouldn't change that steak cut from the shoulder (the chuck) is best roasted or braised due to the relative leanness of the cut compared to other cuts.
Now here's why a flat iron steak is good braised or grilled... because they are not lean relative to the mass of the chuck (typically used for roast, hence chuck roast). This means you don't have to cook a flat iron forever in order to make it tender-- the fatty tissue count is high enough that grilling is all that is needed to break them down whereas a chuck roast (or pot roast if you prefer) must take hours in the oven.
Go to your local butcher and check out the meat case. Look at the marble, the white veins of fat, in the meat. You'll find that meats cut from the hindquarters (strip, sirloin, t-bone, porterhouse, flank) are more marbled than the cuts from the forequarter (the chuck, rib, brisket).
Technically cuts from the middle of the steer are best for grilling, the ribs and loins... however butchers divide the quarters between the ribs and loins because of Jewish dietary law... the hindquarter is not Kosher.
Did I mention he was a Jewish meatcutter?