Preheat the oven to 180C/gas 4. In one, big mixing bowl, cream the butter and sugar together untill smooth. Then in another, smaller bowl, beat the eggs. Pour the eggs into the big bowl and mix. After that, in a different bowl, mash all of the bananas untill you have a paste. Add everything into the same bowl. Make sure that when you put in the bananas and flour, alternate one spoonful of flour and one of bananas. Add the chopped nuts. (the nuts don't have to be chopped, but it makes the mixture easier to mix.) Pour the mixture into a lined 10inch loaf tin. Heat in the oven for about 40-45 minutes untill firm. When you take it out of the oven, leave it to cool for about 30 minutes. Enjoy!