900g/2lb damsons, washed and stalks removed
2 tsp baking powder
100g/4oz caster sugar
100g/4oz caster sugar, plus 1 tablespoon
15g/1/2oz flaked almonds
a pinch of salt
225g/8oz self-raising flour
75g/3oz chilled butter, diced
100ml/4fl oz buttermilk
1 medium egg