[Arran]

There was no tax based on tube count in Britain as far as I can find out. However there was a stigma against higher tube count sets because there was a manufacturer's cartel called the British Valve Association that sold valves/tubes to manufacturer's on a loss leading basis that then gouged customers on replacements, that is according to an article I read in a Radio Craft magazine from around 1946. This was in part the motivation behind sets like the Philco 444 "People's Radio". The author made no mention of a tax on tube counts only the purchase tax which was a big incentive to buy a cheaper radio, and it was cheaper to make and sell a radio with fewer tubes. This was mostly in the pre war era but I don't know if it applied to imported tubes, which is mostly what Philco used. It must have went away by the 1950s however as it's not uncommon to run into a PYE, a Murphy, or a Bush set with more then five tubes, but by then things were more standardized and they were using the same tubes as they did on the continent.
Regards
Arran