Chocolate Orange Drizzle Cake by MollyDunlop

This is a cake my mother used to bake. I have retyped it from an old clipping from a long-forgotten magazine. [quantities are given by weight] 6 oz. luxury margarine (this dates it, I'd use butter)
6 oz caster sugar (superfine sugar)
3 eggs
6 oz self-raising flour (or AP four plus about 2 tsp baking powder)
2 tablespoons milk
finely grated zest of 2 oranges
Orange syrup:
juice of 2 oranges
4 oz sugar
Chocolate topping:
4 oz plain (dark) block chocolate
1/2 oz butter
Grease a 2 lb loaf pan and line with grease-proof paper. Cream the margarine (or butter) with sugar till soft. Beat in eggs one at a time. Fold in sifted flour slowly and add cold milk with last of flour. Add orange zest. Turn mixture into prepared pan and bake in moderate oven (350 F, gas mark 4) for about 1 hour until well risen and golden brown. Turn the cake out onto a rack and allow to cool. When it is nearly cool, make slits across the top with a sharp knife (mother used to attack it with a roasting fork) then drizzle the prepared orange syrup across the top so that it soaks into the cake. When it is completely cool, swirl the chocolate topping over the cake.
To prepare orange syrup:
Mix strained orange juice with the sugar.
To prepare chocolate topping:
Break the chocolate into small pieces and place in a bowl with the butter; allow to melt over steaming water. Mix well and use immediately.