2. Into a medium bowl, sift the flour. Stir in the baking powder, mustard powder, and salt. Stir in the Cheddar cheese.
3. In a small bowl, lightly beat the egg and milk. Mix with the flour mixture and knead for 1 minute until soft.
4. On a floured working surface, pat out the scone mixture into a thickness of 1 inch. Stamp out 2-inch rounds or triangles and place them on a baking sheet.
5. Bake for 15 minutes or until lightly golden. Do not open the oven while baking.
6. Serve warm with butter, jam, or Devonshire cream.