Preheat the oven to 160 degrees C (fan-assisted) and grease or line a 2lb loaf tin.

Break around 2/3rds of the raspberries into smaller pieces with your fingers, leaving the rest to one side.

Place these small pieces in a small bowl and toss with a tablespoon of flour.

Whisk together the caster sugar and margarine.

Add the eggs, whisking in one at a time.

Grate in the zest of 2 lemons and squeeze in the juice of one, saving the other for later.

Whisk well.

Add the flour and whisk until the mixture is smooth.

Fold in the small raspberry pieces carefully, just until they are spread evenly through the batter.

Pour into the loaf tin and spread evenly.

Place around half of the retained raspberries gently on top.

Bake for 45-60 minutes, until the middle, is cooked and the top is golden. I recommend checking after 45 and returning if necessary, checking every 5-10 minutes after, depending on how far off baked it is.

Leave the cake in the tin to cool fully.

In a small bowl use a spoon to mix the icing sugar with the juice of the remaining lemon, until there are no lumps.

Add a little more juice (or water) or icing sugar if needed, until you have a thick drizzle.

Remove the cooled cake from the tin and peel away the baking paper.

Use a spoon, or a piping bag to drizzle over the lemon icing, and top with any remaining raspberries if desired.