Pre-heat the oven to 200°C/400°F/gas 6.
In a bowl, combine the oats and buttermilk and soak for 1 hour. Lightly grease a 12 cup muffin tin, or use paper cases. With an electric mixer, cream butter and sugar until light and fluffy, then beat in the egg. In another bowl, sift flour, baking powder, bicarbonate of soda and salt. Stir into the butter mixture and add the oats and buttermilk and finally the fold in the raisins – do not overmix. Fill the prepared cups two thirds full. Bake for 20-25 minutes.
* If you can’t find buttermilk, add 1 teaspoon of lemon juice or vinegar to the milk and let it stand for a few minutes to curdle.