The Hungarian company Tungsram originally had three valve/tube factories in London, one being the 'British Tungsram Radio Works', in West Road, Tottenham. The brief entry in Graces Guide states that 'British Tungsram' was taken over by Philips/Mullard in 1952. As well as valves, it sold semiconductors, although I have some questions about this. Perhaps the most obvious is: why did it retain the 'Tungsram' branding? It did so, which implies that semiconductors marked 'TUNGSRAM' may not be Hungarian. Such devices cannot, however, bear the Tungsram logo. British Tungsram changed its name to 'Tottenham Road Valve Co. Ltd.' and its branding to 'TORVAC' in the early 1970s. I don't know if this was done for legal reasons. It was apparently dissolved in the latter half of 1978.

If you can provide more detail about British Tungsram, please

Tungsram AC128 transistor

This AC128 in the standard TO-1 package comes in a rather nice metallic tube that bears the words 'TUNGSRAM SEMICONDUCTORS' plus the Tottenham address, and was therefore made by 'British Tungsram', although the transistor itself is unbranded. It is a germanium PNP AF output type and is probably a Mullard device. It raises the probability that British Tungsram did not manufacture semiconductors, but just re-packaged Mullard types.

Hungarian Tungsram also made AC128, but in their typical TO-1A outline, and bearing their logo.

Tungsram OC1079 transistor

This is an OC1079, equivalent to an OC79 AF output driver in an outline similar to the Philips/Mullard SO-2 original. It is printed TUNGSRAM rather than bearing the logo, which raises the possibility that it was made by British Tungsram, although the construction does not look exactly like a Mullard type and the addition of 1000 in the part number is typical of Hungarian Tungsram. I would welcome information about this type.

TORVAC OC75 transistor

British Tungsram changed its name to 'Tottenham Road Valve Co. Ltd.' in the early 1970s. It certainly sold some Philips/Mullard transistor types and printed 'TORVAC' on them. My image shows an OC75 printed 'TORVAC' and stored in a 4-inch tube (longer than that of the AC128 above) that is printed 'A PRODUCT OF TOTTENHAM ROAD VALVE CO. LTD., ENGLAND' but does not bear an address. I would be interested to find more such types, or any TORVAC semiconductor data literature. If you can help, please