Cut a double thickness of greaseproof paper, 15cm larger than the diameter of the bowl. Butter the paper and fold a pleat into the centre (this is to allow the pudding to expand as it cooks). Cut a piece of string long enough to tie the paper to the bowl. Add water into a lidded saucepan to come halfway up the sides of the pudding basin, Bring to the boil.
By hand or in a mixer, beat together the sugar and butter until light and fluffy. Beat in the eggs and vanilla a little at a time.
Gently fold the flour into the butter and sugar. Fold in enough milk to give a soft, light batter. Spoon the batter over the marmalade.
Place the greaseproof paper over the pudding basin and tie it tightly under the rim of the basin.
Carefully place a trivet, saucer or biscuit cutter in the bottom of the pan so that the bowl doesn’t touch the bottom and then lower the bowl into the pan. Place a lid over the pan and steam for 1 hour 30 minutes. Check from time to time to make sure the water comes halfway up the side of the bowl. Top up if necessary.
Carefully lift it from the pan, remove the paper and run a knife around the edge of the bowl to loosen the pudding. Place a plate over the top of the bowl and invert the pudding on to the plate.