Preheat your oven to 140 fan assisted / 160 conventional / gas mark 3.
In a bowl, cream together the butter and sugar. Crack in the eggs one at a time and beat thoroughly before adding the next. If needs be, you can add a teaspoon of plain flour between each egg so the mix doesn’t split,
Add the two flours and mix well.
Fold in the zest and oil / flavouring and combine well.
Scrape the mix into a lined loaf tin and bake for an hour – test the middle of the cake with a skewer and if it comes out clean, the cake is ready. Dependent on your oven, it may take longer to cook so just keep testing at 5 minute increments.
For the drizzle
Heat the juice of the two lemons and orange in a saucepan and dissolve the 100g caster sugar and the icing sugar into it. When your loaf has finished cooking, pour your drizzle all over the top of the cake. As it cools, the drizzle will get a nice glaze to it and it will crack beautifully when you cut into it.