Heat half the margarine in a large frying pan until hot. Add 6 of the Fish Cakes & fry over a moderate heat for 3 - 4 minutes on each sides, until nicely brown. Place onto kitchen paper to drain & keep in a warm place until the others are ready. Wipe out the pan, add the remaining 2 oz margarine & repeat for the remaining 6 Fish Cakes. Drain on kitchen paper & serve.