Leaven
Weigh the leaven into a bowl, add the water and flour and mix well with a dough whisk or fork.
Leave for 4 hours
The batter
Add both the flours and the caster sugar to the leaven.
Add the milk and mix well with a dough whisk
Cover and leave overnight. The mixture should rise and then fall back a little.
In the morning
Mix the lukewarm wayer, bicarbonate of soda and salt in a jug
Stir in the contents of the jug thoroughly into the bowl with the dough whisk
Leave to stand for 20 minutes. You should see bubbles start to form in the combined mixture.
Heat a skillet or heavy frying pan, lightly oiled with sunflower oil, to medium heat
Grease the crumpet rings
Place the crumpet rings in the pan and spoon in the batter to about 1cm thick (for most rings this would be half way or just slightly less)
The crumpets should heat through gently. The batter will rise. Cook until bubbles form all over the surface. As it sets, do move the crumpet ring just a little to ensure it is not sticking.
When the surface is completely set, turn the crumpets over. Remove from the pan after one minute
Gently remove the crumpets from the rings and serve immediately with butter