Grease a 5-cup ovenproof bowl with butter and spoon the syrup into the base.
Beat the butter and sugar together in a bowl until soft and creamy, then beat in the eggs, a little at a time,. Fold in the flour and stir in the milk to make a soft dropping consistency. Add the lemon rind. Turn the mixture into the oven proof bowl.
Cover the surface with a circle of waxed or parchment paper and top with a pleated sheet of foil. Secure with string or crimp the edges of the foil to ensure a tight fit around the bowl.
Put the pudding in a large pan half-filled with boiling water. Cover and return to a boil over medium heat. Reduce the heat to a slow simmer and steam for 1 1/2 hours, or until risen and firm. Keep checking the water level and top off with boiling water as necessary.
Heat a little more corn syrup in a pan. Remove the pudding pan from the heat and lift out the ovenproof bowl. Remove the cover and loosen the pudding from the sides of the bowl using a knife. Turn out into a warmed dish and serve with the extra corn syrup.