I use Lord Sheraton Pure Beeswax Balsam polish which is available from your Asda, Tesco, etc supermarkets for less than a fiver, this is perfect for all of my guns and gives a good shine.
Smells nice as well
I was told by a friend who had an old BSA in walnut that the only thing he ever used to keep
it pristine was walnut oil from the supermarket (under £2) and the bottle seems to last forever.