Makes about 24 small sandwiches.
Preheat oven to 425°F. and butter a large baking sheet.
Into a large bowl sift together flour, baking powder, and salt. Cut butter into small bits and with your fingertips or a pastry blender blend into flour mixture until mixture resembles coarse meal. With a fork stir in Cheddar. Add milk and cream, stirring until just combined. Transfer mixture to a floured surface and with floured hands knead until it forms a dough. Roll out dough into a 12-inch round (about 1/2 inch thick). Using a 2-inch fluted round cutter cut out scones and arrange about 1/2 inch apart on baking sheet. Gather and gently reroll scraps. Cut out more scones and arrange on baking sheet.
Bake scones in middle of oven until pale golden, about 12 minutes, and transfer to a rack to cool. Scones may be made 1 day ahead and kept in an airtight container at cool room temperature.
In a small bowl stir together butter, mustard and honey. Tear each lettuce leaf into 4 pieces. Split scones and spread each split side with honey-mustard butter. Make sandwiches with scones, lettuce, and folded slices of ham.