Preheat the oven to 180 degrees C (fan 160C/350F/Gas 4). Grease a 1.7 litre ring mould that is 23cm in diameter and 7.5cm deep. Cut about 8-10 strips of baking parchment, each 15 x 2.5cm, and use them to line the mould.

Place the butter, caster sugar, flour, and baking powder in a large bowl. Add the eggs, milk, and lime rind and beat using an electric hand whisk for about 2 minutes (or 3 minutes with a wooden spoon) until smooth.

Spoon half the mixture into the ring mould and level it, then scatter the blueberries over the top, keeping them away from the edge of the mould (this makes them less likely to stick). Spoon the rest of the mixture over the blueberries, and spread it evenly with a palette knife to cover the fruit.

Bake for 35-40 minutes or until well risen and the top springs back when lightly pressed. While the cake bakes, make the glaze: mix the lime juice with the granulated sugar and set aside. Leave the cake to cool in its tin for a few minutes, then loosen the side with a palette knife. Turn it out onto a wire rack set over a baking tray, and peel off the lining strips.

While the cake is still warm, prick all over with the skewer. Stir the glaze, then spoon it over the warm cake. Leave to cool completely.