This is my Great Grandmother's recipe which has been passed down to me.  My Mum says that she always remembers a tin of these being in the farmhouse pantry.

1lb (450g) plain flour
12oz (335g) butter
4oz (115g) sugar
1 tsp caraway seeds

1. Place all ingredients in a bowl and rub the mixture until it all comes together
2. Roll out until its about 1 cm thick.  Cut into rounds.
3. Bake in a slow oven - approximately 140 C/280 F for approximately 40-50 minutes.  The secret to a good sugar cake is keeping the biscuit as pale as possible.
4 Sprinkle with caster sugar and cool on a wire rack.
5. Store in an airtight tin and should you be able to resist they will keep for weeks!