To make the cake we preheat the oven to 170℃ and line a 9inch loaf tin by brushing it with butter and adding baking paper.
In a large mixing bowl add the castor sugar, lemon zest and rub together with your fingers for a couple of minutes.
Add the butter and beat with an electric beater until pale and creamy.
Add the eggs, one at a time and beat well between each egg. Add the vanilla and beat again.
Add the flour, baking powder, baking soda, salt into a sieve and sift the dry ingredients into the egg mixture. Beat well until its all combined.
Add the lemon juice and fold together, scraping the sides and mixing well.
Pour the batter into the baking tin and bake for 40-45 mins until risen and a tooth pick inserted into the center comes out clean.
While it is cooling down make the drizzle by mixing the castor sugar, lemon zest and juice in a bowl until combined.
Pour this over the warm cake and let it soak up all the syrup. Leave it to cool in the tin for a couple of hours.
Remove from the tin, slice and serve. The top will have formed a crust and that is perfect.