1. In a mixing bowl, combine flour, sugar, salt, and baking powder.
2. In another bowl, mix warm milk and yeast. Let it sit for 5 minutes.
3. Pour the milk mixture into the dry ingredients. Whisk until smooth.
4. Gradually add warm water, whisking until you have a smooth batter.
5. Cover the bowl and let the batter rise for about an hour.
6. Heat a frying pan over medium heat and grease with vegetable oil.
7. Place crumpet rings in the pan and pour batter into each ring.
8. Cook until bubbles form on the surface, then remove the rings and flip the crumpets.
9. Cook for another 2-3 minutes until golden brown.