Emerson small woody.

[Yorkie]

I don't know how you find these things, David. You must have a talent for nosing out oddball video clips! Perhaps Lawrence has, too, or did you discover this yourself, Lawrence? Either way, a useful tip.
Tony

I entered a search string into google 'find numbers on old radio valves with a torch' Tony. Luckily, that link came up at the top of a very long list!

Really, I need to get out more!

I've mentioned before that a good way of checking if a TV remote is working is to point it into the lens of a digital camera and if all is well, it will light up ultra violet in the view-finder screen. The camera can see it - we can't, and neither, incidentally, can birds. That's why you can use UV LEDs to light up a bird-box so that a pinhole camera can show how the nesting birds are progressing. Neat eh, and utterly irrelevant to this threadfind numbers on old radio valves with a torch