Preheat the oven to 180 C / Gas 4. Line a square baking tin with baking parchment.
In a saucepan on a low heat combine the margarine or butter, brown sugar and the golden syrup or honey till it is all melted and runny then mix in the oats until well coated. Spoon the mixture into the prepared baking tin and press down gently with the back of a spoon to compact the mixture.
Bake in the preheated oven for 20 to 25 minutes until golden brown. Remove from the oven and mark into squares. Allow to cool in the tin then remove using the baking parchment to help you. Cut into squares and serve.