Preheat the oven to gas 4, 180°C, fan 160°C. Grease and line a 1kg loaf tin with non-stick baking paper.
In a large bowl, beat together the butter and sugar until light and fluffy. Add the eggs one by one, beating in well. Add the vanilla, and zest and juice of 1 lemon. Fold in the self-raising flour and almonds until well mixed.
Pour into the tin and bake for 55-60 mins. Allow to cool in the tin for 15 mins, then remove and let cool completely.
Mix the icing sugar with a little lemon juice to make a thick, pourable icing. Spoon over the cake and serve.