Put the flour, yeast, sugar and lemon rind in a bowl. Melt 40 g (1½ oz) of the butter. Beat the egg with the milk, melted butter and almond extract and add to the bowl. Mix with a round-bladed knife to make a soft but not sticky dough. Turn out onto a lightly floured surface and knead for 10 minutes until smooth and elastic.
Place in a lightly oiled bowl, cover with clingfilm and leave to rise in a warm place for 1½ hours or until doubled in size. Grease an 18 cm (7 inch) square cake tin, preferably loose based. Turn the dough onto a floured surface and roll out to a 50 x 15 cm (28 x 6 inch) rectangle. Spread with the soft butter and scatter with chopped sour cherries and muscovado sugar.
Roll up the dough from a long edge, so it forms a thin log, and cut across into 16 even-sized pieces. Lay the slices in the tin, cut sides up. Cover with oiled clingfilm and leave in a warm place for about 1 hour until the dough has risen. Bake in a preheated oven, 220°C (425°F), Gas Mark 7, for 25 minutes until risen and golden. Leave for 5 minutes then transfer to a rack to cool. Mix the syrup and lemon juice and use to glaze.