Wholewheat Banana Nut Loaf

I found this recipe from book called The Great Big Baking Book by Carole Clements. I made small changes and I loved it. It is very moist inside and little crunch from walnut. mmmmmm Delicious. 

Ingredients
MAKES ONE LOAF
4 oz (115 gr) butter,at room temperature
4 oz (115 g) brown sugar
2 eggs, at room temperature
4 oz (115 g)  plain flour
1 tsp bicarbonate of soda
1 tsp baking powder
1/4 salt
1 tsp ground cinnamon
2 oz (55 g) wholewheat flour
3 large ripe bananas
1 tsp vanilla essence
4 oz (110 g) walnut
Preparation Method
1-Preheat a 350 F / 180 C oven. Spry oil a 9x5 in (23x13) loaf tin.
2-with an electric mixer, cream the butter and sugar together until light and fluffy.
3-Add the eggs, 1 at a time, beating  well after each addition.
4-Sift the plain flour, bicarbonate of soda, baking powder,salt and cinnamon over the butter mixture and stir to blend.
5-stir in the wholewheat flour.
6-with fork ,mash the bananas to a pure, then stir into the mixture. Stir vanilla and nuts.
7-Pour the mixture into the prepared tin and spread level.
8-Bake until a skewer inserted in the center comes out clean, 50-60 minutes. Let  stand 10 minutes before transferring to a rack.