Hi dollychris, the recipe i use goes as follows:
3oz pudding rice
2oz sugar
1 pint milk
small can of evaporated milk
butter
grease an ovenproof dish with butter, rinse rice and then put into dish along with sugar and milk. put 4/5 knobs of butter on top and sprinkle with nutmeg. cover and cook for 1 hour in oven on 150. After an hour stir well then add the tin of evaporated milk. Cook for another hour and then enjoy lovely creamy rice pudding. Mine's just going in the oven now....mmmmmm.
Sorry don't really know about how to make it runnier ;-)