Put the butter in a bowl, sift in the flour and rub together until the mixture resembles fine breadcrumbs. Add the sugar and lemon rind and stir everything together with a wooden spoon. Add most of the egg and stir again until the mixture comes together, then use your hands to draw the dough together into a ball.
Pick off small pieces of dough and roll them into balls, each about the size of a cherry. Press 8 balls of the cookie dough together into a circle, then repeat to make a further 5 garlands. Place small pieces of glacé cherry or angelica between the balls.
Place the garlands on a baking sheet lined with nonstick baking paper and bake in a preheated oven, 190°C (375°F), Gas Mark 5, for about 15 minutes or until pale golden. Just before the end of the cooking time, brush with the remainder of the egg and sprinkle with caster sugar, then return to the oven to finish cooking.
Remove from the oven and allow to cool a little before transferring to a cooling rack. Thread on to ribbons and use as decorations.