Heat the oven to 180C (160C fan, Gas 4). Grease and line a loaf tin with enough baking paper to leave a small overhang.
In a large bowl add the sugar, flour, butter, eggs, lemon zest and baking powder. Beat together with an electric whisk until smooth.
Pour the cake batter into the prepared cake tin and promptly place it on the middle shelf of the oven. Bake for 40 minutes or until golden brown.
Meanwhile, make the lemon drizzle topping by mixing together the sugar and lemon juice.
When the cake is out of the oven and still warm, carefully spoon over the drizzle mixture.
Once the cake is cool, lift it out of the tin and slice.
