Preheat the oven to 140C/275F/gas 1.
Generously grease the baking tin with butter.
Place the treacle, syrup and butter in the saucepan and place over a medium heat until melted together, being careful not to let the mixture boil.
Take off the heat and set aside.
Place the flour, oatmeal, ginger, sugar and salt in the large mixing bowl.
Make a well in the centre, pour in the treacle mixture and stir in thoroughly.
Place the milk in the measuring jug, add the eggs and beat in.
Add this to the Parkin mixture and stir in thoroughly.
Transfer the mixture into the cake tin and place in the oven.
Bake for an hour and a half or until just firm in the centre when pressed.
Remove from the oven and allow to cool in the tin for at least half an hour before turning out onto the cooling rack.
Allow to cool to room temperature. Wrap in 2 layers of kitchen foil and store in an airtight container for at least 3 days.
