Heat the oven to 180C/160C fan/gas 4. Butter 900g loaf tin (about 25cm long) and line with baking parchment. Beat the butter and sugar together in a stand mixer or using an electric whisk for 3-4 mins until light and creamy. Gradually crack in the eggs, one at a time, beating well after each addition.

Combine the flour and baking powder in a bowl. Beat the lemon zest and juice into the wet ingredients until combined, then gently fold in the flour mixture. Spread the batter into the prepared tin and smooth the surface. Bake for 40-45 mins until golden and a skewer inserted into the centre comes out with just a few crumbs clinging to it. Remove from the oven and leave to cool in the tin for 10 mins, then remove from the tin and leave to cool completely on a wire rack.

For the icing, sift the icing sugar into a bowl and add 3 tbsp of the lemon juice. Whisk together, adding more lemon juice, a teaspoon at a time, until the icing is thick but drizzly. Drizzle the icing over the cooled cake and leave to set for 15-20 mins before slicing.