You may come across thermionic valves/tubes or germanium semiconductors marked HALTRON. This was the brand of Hall Electric Limited in London. Before about 1952 they were based in Charlotte Street, then they moved to in Lisson Grove, by 1961 their address was Haltron House, Anglers Lane, London, NW5 and in 1977 it was Electron House, St. Mary Cray, Orpington, Kent. They were an export-only business that seems to have bought up surplus stock from electronics manufacturers, re-branded it, and sold it overseas. They have an entry in Grace's Guide that is empty apart from a couple of images of advertisements, and a short entry on radiomuseum.org. It seems likely that the bulk of their business was in thermionic valves/tubes and that semiconductors were a minor part.
Hall Electric advertised their valves/tubes in Wireless World and a Web search will find advertisements from the 1950s up to 1977. One from April 1961 claims 'We have the most comprehensive stock in the world of receiving, special purpose, transmitting tubes and also transistors, totalling over 3,000 types.' Quite a boast! A July 1977 advertisement has dropped the 'export only' emphasis, and shows integrated circuits rather than valves, which suggests that their marketing had changed. I do not know when the company ceased trading.
I have seen on eBay a transistor radio 'Haltron Mk8', claimed to date from the 1960s, sold by a company called 'Global Imports' at the Haltron House address. The radio was made in Hong Kong and does not contain English transistors. A Web search produces evidence of a Mk7 and a Mk1 at least. This would appear to be an import business connected with Hall Electric.
If you know more about Hall Electric please
Here is a Haltron OC45, the classic early germanium PNP alloy-junction low-power intermediate-frequency amplifier. It's in the JEDEC TO-1 outline, not the standard Mullard/Philips SO-2 glass, although Mullard did make a later TO-1 version.
And here are two rather nice OC74 germanium PNP low-power audio-frequency amplifier transistors. They use the classic VASCA SO-2 metal outline however they do not seem to have the Mullard/Philips-style glass tube inside.
I have seen images on the Web of Haltron-branded OC77s and OC123s in TO-1 outline, plus listed stock of Haltron OC70s. I'm unaware of any other Haltron semiconductors.
If you know more about Haltron semiconductors, or have any, please