For the spotted dick, place the flour, baking powder, shredded suet, caster sugar, currants and lemon zest into a bowl and mix to combine.
Add the milk and stir to make a soft dough.
Grease a pudding basin with butter and spoon the mixture into the basin. Cover with a piece of folded greaseproof paper.
Tie around the edge with string to secure the paper and place a damp tea towel over the top. Tie once more with string to secure the tea towel.
Place the basin into a large lidded saucepan and fill the pan two-thirds of the way up with water.
Cover with the lid, bring to a boil and simmer for one hour.
For the custard, place the milk and cream into a saucepan and bring to a simmer.
Place the egg yolks and sugar into a bowl and whisk together until light and frothy.
Pour the hot milk onto the eggs, a little at a time, and stir well. Pour the mixture back into the pan and cook over a low heat, stirring with a wooden spatula, until just thickened.
To serve, slice a wedge of spotted dick for each person and place onto each of six plates. Pour over the custard and serve at once.