Put the golden raisins and rum or bourbon in a smallish saucepan and bring to the boil. Remove from the heat, cover, and leave for an hour if you can, or until the raisins have absorbed most of the liquid, then drain.
Preheat the oven to 325°F and get started on the rest. Put the flour, baking powder, baking soda, and salt in a medium-sized bowl and, using your hands or a wooden spoon, combine well. In a large bowl, mix the melted butter and sugar and beat until blended. Beat in the eggs one at a time, then the mashed bananas. Then, with your wooden spoon, stir in the walnuts, drained raisins, and vanilla extract. Add the flour mixture, a third at a time, stirring well after each bit. Scrape into the loaf pan and bake in the middle of the oven for 1-1¼ hours. When it’s ready, an inserted toothpick or fine skewer should come out cleanish. Leave in the pan on a rack to cool, and eat thickly or thinly sliced, as you prefer.
I haven’t done a tremendous amount of fiddling with this recipe, but I did once make it, for friends who are more chocolate-crazed than I am, by replacing 2 tablespoons of the flour with good cocoa powder and adding 4 ounces of bittersweet chocolate, cut up into smallish chunks. And you could just as easily use the chocolate chips sold in the baking aisle of supermarkets.