Mix 1 cup of the warm milk and all of the sugar in a small bowl.
Sprinkle yeast on top of the milk and let sit for ten minutes.
While you are waiting, mix bread flour, all-purpose flour, salt, and baking soda in a medium-sized bowl.
Add the yeast mixture, the remaining 1 1/2 cups of warm milk, and the water, to the flour mixture and stir to combine. If you've made bread before and are used to a thick dough that you can knead, don't expect that from this batter. This will be a thick liquid, almost like a milkshake (don't drink it - yuck!).
Cover the batter and set in a warm place to rise for about an hour.
Heat a non-stick skillet or griddle to medium-low heat (I used setting 3 on my range, but yours may differ).
Butter the insides of your crumpet rings and place them on the skillet.
Fill each crumpet ring halfway.
After four minutes, you should be able to remove the rings using tongs. You can wait longer, but the longer I waited, the more the crumpets stuck to the rings.
Stare at the crumpets. It's fun! You'll notice bubbles forming and popping. It's like a trip to Yellowstone, but much cheaper. After about five minutes, you won't see any more bubbles forming or popping and you'll be able to tap the tops of the crumpets and hear a sound (meaning the tops have hardened a bit). It's now time to flip them!
Some people don't flip their crumpets at all, but I like to flip mine and cook for just a minute. It will give what will become the crumpets' tops an ever-so-slight browning.
Serve immediately with Lyle's golden syrup (shown in the photo), clotted cream and jam, or honey and butter; or cool, cover, and toast before serving.