Triple berry Christmas cake

Ingredients

• Little sunflower oil for greasing
• 225g (8oz) soft margarine
• 225g (8oz) caster sugar
• 225g (8oz) self-raising flour
• 1 teaspoon baking powder
• 4 medium eggs
• 1 lime, grated rind only
• 1 lemon, grated rind only
• 1 x 325g jar lemon curd
• 225g (8oz) raspberries, plus few extra to decorate
• 400g (14oz) strawberries, thickly sliced, plus few extra to decorate
• 150g (5oz) blueberries
• 450ml (3/4 pint) double cream
• 100g (4oz) coconut shavings
• Little icing sugar, sifted, to decorate