Heat the milk gently until just warm.
Add the caster sugar and yeast to the warm milk and stir. Leave for about 10 minutes until the mixture starts to get a little frothy.
Sieve the gluten free flour, bicarbonate of soda and salt into a large mixing bowl.
Add in the frothy milk mixture. Using an electric whisk, mix until smooth.
Cover the bowl with lightly oiled cling film and leave to prove, covered in a warm place for about 90 minutes (there should be some air bubbles on the top once it's done).
Heat a frying pan to a medium heat and, once hot, add a tbsp oil. Place either a couple of egg rings or biscuit cutters in the pan.
Once the pan is hot enough, put two and a half tbsp of the batter in each ring and allow to cook for about 5 minutes. Little air bubbles should start to appear on the surface.
Flip the crumpets over and cook the other side for a minute or two.
Remove from the pan and repeat with the rest of the batter.
Serve hot from the pan or simply reheat in a toaster. Delish served with butter and golden syrup/maple syrup/jam.