Wartime radios relied on valve technology, the modern transistor not having been invented at this point. Valves were made of glass and were both physically and electronically fragile, it not taking much to either smash them or burn out the interior components. In order to be able to replace these critical components in the field if they were to fail, signallers were taught how to maintain and replace these valves and all radios were issued with a set of spare valves. Due to the fragile nature of these valves, the case to hold the spares had to be robust on the outside to withstand rough treatment, and padded on the inside to protect the valves themselves. As part of my ongoing project to build up a WS19 set and its accessories, I have acquired this spare valve tin to accompany my radio:
The case is made of steel and has a hinged lid, secured with a rotating hook. On the top of the case is a webbing handle to allow it to be easily carried:
The front of the case was originally marked up to show it was for the spare valves for the 19 and 22 set radios. At some point in the 1950s, this was over-painted and a simple stores code added instead:
Sadly the original padded lining, which would have been made of rubberised horsehair, is long gone, however under the lid is a paper label showing how the contents would have originally been packed:
These valve cases survive because, with the inner liners pulled out, they made a useful storage tin, cheaply available as surplus in the 1950s. This example is not in brilliant shape, however it is acceptable enough to accompany my radio until a better example comes along.
Tales from the Supply Depot 
I remember when there was a tube tester and tubes in every department store for radios and TV’s, today you can’t repair anything in them yourself and it’s cheaper to buy a new set.
A capacitor blew in a microwave a few years ago, I can fix that but the replacement part was $60 and a new microwave was $79.
Once upon a time, back in the 80’s, I worked on torpedos intended to be dropped on Warsaw pact submarines.
One of them used tubes, as did the test equipment, and printed on the box every replacement one came in was “made in Czechoslovakia” a Warsaw Pact country…
Our standard saying was that we didn’t get the updated manuals until the Soviets signed off on them, and I’m not entirely sure it wasn’t accurate.
There’s a whole range of those cases (Spare Valves, No.4_) for different wireless sets – I think they got as far as the suffix ‘L’, or maybe ‘P’ for the postwar SR C12. They were manufactured by various companies and had different lid catches (Hook, like on this one, spring strip with a hole in it, or a toggle latch), and there were four different insert types just for the 4G used by WS19 or WS22: “Rubberised animal hair” – there was a trade name for this but I’ve forgotten it – it was made in flat sheets so the compartments were square; black sponge rubber (which has an annoying tendency to liquify with age and stick to everything); resin bonded paper – which is the one for your case (valves are kept in the original waxed paper wrappers as there’s no padding in the case); and the US or Canadian made cases with a stamped metal ‘chassis’ and actual sockets to hold the valves. As noted: you can find the cases but the inserts have been discarded.
“Resilitex” is the stuff I was thinking of – most often found in the flat spare valve cases (4 Valve No.3 and Cases, Spare Valve, No.2T).
https://archive.commercialmotor.com/article/19th-march-1943/20/shock-absorption-by-a-spongy-textile