1) Preheat the oven to fan 160C/ conventional 180C/gas 4. 2) Butter a 20 x 13cm loaf tin and line the base with greaseproof paper. 3) In a large bowl, whisk together the butter and sugar with an electric whisk until creamy. 4) Beat in the eggs one at a time (don’t worry that the mixture looks curdled). 5) Stir in the mashed bananas, pecans, raisins and buttermilk. 6) Sift the flour and bicarbonate of soda on top of the banana mixture, then fold in until evenly mixed, taking care not to over mix. 7) Spoon into the prepared tin and level the top. 8) Bake for 1 hour 15 minutes until a skewer pushed in the centre comes out almost, but not quite, dry. 9) Remove from the oven and leave for about 10 minutes, then turn it out of the tin on to a cooling rack to cool. 10) For the icing, mix the icing sugar with 2-3 tsp cold water to give a smooth, runny consistency. Using a dessert spoon, drizzle the icing in lines across the loaf.