Pre-heat the oven to 160C Fan/350F/Gas Mark 4 and grease and line a 2lb loaf tin
Mix together the butter and caster sugar using an electric mixer or a spoon until light and fluffy, around 3 minutes
Add the eggs and milk and whisk in until well incorporated
Before you whisk in the flour, take away a spoonful and mix it into the blueberries to fully coat them with flour. Then whisk the remaining flour into the cake mixture gently until fully combined
Fold in the lemon zest
Put a layer of the cake batter, about 1cm deep into the base of the lined tin
Then gently fold the blueberries into the remaining cake batter
Pour the batter into the loaf tin and bake for 1 hour, or until a skewer inserted in the centre comes out clean. Leave to cool fully
Mix the lemon juice with icing sugar until you get a pourable consistency, drizzle it all over the cake
Add some blueberries and lemon zest to decorate if you like
Store in an airtight container in a cool place and eat within 3 days