Make topping first; rub in marge and flour, then rub in sugar and cinnamon. Grease and flour an 8inch cake tin.
Rub in flour and marge and then add sugar, egg and milk. OR you can cream the marge and sugar and then add the egg and flour and milk. Stir for about 1 min until a batter is formed (sloppy). Put into tin and spread evenly.
Cover the cake with the topping and bake at 375/400 (or gas mark 6, or 190-200C) for 45 min. If cake starts to burn, cover with greaseproof paper (or a flat tin) to prevent the top getting too brown. Be sure the tin is deep enough so the batter does not rise to meet the cover! I usually put some mixed spice in the cake mixture too