Heat the oven to 180°C conventional, 160°C fan or 350°F. Grease and line a 900 g/2 lb loaf tin, approximately 23 x 13 cm, with baking parchment.

Toss the blueberries with 1 teaspoon plain flour and set them aside. The light flour coating helps reduce sinking and limits excess moisture in the crumb.

Rub the lemon zest into the caster sugar with your fingertips, then cream the scented sugar with the softened butter for 3–5 minutes until pale and fluffy.

Beat in the eggs one at a time. If the mixture begins to look curdled, add a spoonful of the flour before adding the next egg.

Fold in the self-raising flour, baking powder and salt if using plain flour, mixing only until combined. Add the milk only if the batter is especially thick; it should be thick but spoonable.

Fold in the floured blueberries gently, taking care not to crush them. Transfer the batter to the prepared tin and level the surface.

Bake for 50–60 minutes, or until golden and a skewer inserted into the center comes out clean or with a few moist crumbs.

While the cake bakes, mix the granulated sugar and lemon juice for the drizzle. Keep the sugar slightly granular rather than dissolving it completely, since this creates the characteristic crisp lemon topping.

Leave the baked cake in the tin for 10–15 minutes. Pierce the top repeatedly with a skewer, then spoon the lemon drizzle over the warm cake so it can soak into the crumb.

Cool the cake completely before removing it from the tin. If desired, mix the icing sugar with 1 1/2–2 tablespoons lemon juice and drizzle it over the cooled loaf, then scatter over extra lemon zest.