Preheat the oven to 375 degrees.
Sift the dry ingredients into a large mixing bowl.
Cut the butter into the mixture with a pastry blender or two knives until the mixture resembles coarse meal. (This can also be done in a food processor, using half the flour mixture. Add to the remaining flour in bowl before adding cream.)
Mixing lightly with your fingers, add heavy cream just until the dough holds together. Wrap in plastic and chill about ½ hour before rolling out.
Roll the dough into a circle, ½ inch thick for small scones and ¾ inch thick for larger ones. Using a biscuit or cookie cutter, cut the dough into various shapes. (I used a heard shaped cutter and a scalloped biscuit cutter.)
Butter a large baking sheet and place the scones on it. Combine the egg and light cream in a bowl and brush the tops of the scones with the mixture.
Bake until golden brown and puffed, 13 to 15 minutes. Serve with herb jellies.