Preheat oven at 150 degrees / gas mark 2.

Melt the butter in a saucepan and using a pastry brush - brush melted butter to grease a lined 20 cm or 8 inch square tin.

Add the golden syrup and light soft brown sugar. Mix well and remove from heat. Add the grated lemon zest and porridge oats.

Press the mixture down firmly into the baking tin. Bake for 40 minutes till golden brown.

Remove from the oven and using a sharp knife divide them into 16 squares.

Let the mixture cool in the tin for 15 minutes. Remove from the tin onto a chopping board. Use the sharp knife to break the pieces off carefully.