No, Spaw; don't know what a sourdough crumpet is. The point of our crumpets, & what differentiates them from such relatives as [our] muffins, Scotch pancakes, &c, is that they are honeycombed with holes thru which the butter, jam &c, permeate. Delicious.

There is a sort of folktale [I think] that their recipe, the kind of flour used, and so on, are terribly hush-hush & secret and known only to the bakery trade...

~M~