Heat the milk with the lemon zest to just below boiling point. Remove pan from the heat and set aside to infuse.
Meanwhile, butter the slices of bread and cut each slice into quarters to make twenty four triangles in total, leaving the crusts on. Arrange the bread in layers, buttered side up, neatly overlapping in a well greased, 1.5 litre rectangular, ovenproof dish, scattering the apricots in between the layers.
Beat together the eggs, caster sugar and flavoured milk. Pour the mixture over the bread and leave to soak for 30 minutes. Gently push the bread down into the custard so that each piece is soaked.
Preheat the oven to 180°C (gas 4). Mix together the demerara sugar and cinnamon and dust over the top of the pudding.
Bake for 40–50 minutes or until the custard is lightly set and the top is golden brown and crusty. Leave for 5 minutes before serving.
*If you have a jar of mincemeat, spread a layer in between the layers of buttered bread in place of the apricots. *This pudding can be served with cream, but is better still with vanilla ice-cream.