The Mentmore Manufacturing Company opened in 1919. It was named not after the founder in the usual fashion of the day but rather for Mentmore Terrace in London where they had their initial existence. It seems that, despite the somewhat generic name, their first output was a self-filling pen.
In 1925, Mentmore introduced the Platignum sub-brand, which used stainless steel points and which Mentmore wanted to reassure the buying public about by using “As Good as Gold” in their advertising. Their initial impulse was to use “Platinum” as a brand name, but British regulations of the time demanded that if the name of a substance were used in an advert, the substance itself had to appear in the product. This rather defeated the purpose of a bargain brand, so the odd spelling was adopted (and we may assume that the second syllable rhymes with “sign” rather than “pig”). Platignum was notable in a couple of ways, as it was an early example, indeed likely the first, of injection molding for pens, and it also introduced the notion of interchangeable points rather in advance of Esterbrook, having both in production in the late 1920s. Mentmore became publicly traded in 1930, which was something of a kiss of death for pen companies in the 1980s, but appears to have done no serious harm in this instance.
The advent of the Second World War saw the company scale back production substantially, through restrictions on material, loss of manpower, and a turning away from pens to production of the fiddly bits of the engines of war. Pen production did go on, however, and some of that production was directly related to the war, as they produced some very James Bond-ish items in pen form, including a poison-dart pen. An interesting note on the British restrictions, and one I’d like to confirm better at some point; rather than mere restrictions on quantities of material used, it seems that there were on pen makers restrictions on the number of models that could be offered. Initially five was the limit, dropping to two, and going back up to five in 1946 (because rationing persisted in England until, in my understanding of pop-culture references, 1982).
After the war, production was resumed, from some deeply-reviled bottom-end Platignum school pens up to the Mentmore `69′ which was clearly named and designed in emulation of the Parker “51” . I have read a claim that the invention of the modern ink cartridge was a Mentmore/Platignum effort in about 1950, something usually ascribed to Waterman and three years later, but the company’s long experience with injection molding makes me hesistant to call out vigourously against the claim. Another reference indicates that Platignum didn’t offer a cartridge pen until 1965, though, which is more in keeping with orthodox notions of pen history.
It seems that all went reasonably well for the Platignum side of things, at least, up to 1997, at which point they were bought up by a printing company. I hedge the previous statement because the few sources I can find stop speaking of Mentmore altogether in the 1950s, and I honestly don’t know if the company was absorbed by its budget offspring in a manner similar to Eclipse or just elevated the popular name to the fore. I suspect that, unlike the current incarnation of Platignum which seems to be in direct connection with the history above, the company currently calling itself Mentmore is a band of resurrectionists of the same sort as currently offer Conklin pens and have simply bought themselves an evocative name. There’s nothing wrong with this, although a little more might have been done to disguise Chinese makers of the components. Update: An informant says of Mentmore’s hidden years that they became little more than the plastics wing of Platignum, and were absorbed by Tatra Plastics after passing though a period of being Copa-Mentmore, being lashed in either partnership or subdivisionhood with the pre-existing Copa company. The informant became aware of this through working for Tatra.
Models I’ve examined: