Preheat the oven to 180 C / Gas 4. Grease a 18x28cm baking tin and line with baking parchment.
Place the margarine, sugar, and golden syrup in a saucepan and stir over low heat until the margarine has melted. Stir in the bicarb followed by the flour, oats and currants. Transfer the mixture to the prepared tin and press gently into the base and sides with the back of a spoon to compact.
Bake in the centre of the preheated oven for 15 minutes until golden brown. Remove from the oven and allow to cool for 10 minutes in the tin before removing and continuing to cool on a wire rack. Cut into bars and serve.
Brown sugar can also be used to give a darker taste.