I haven't encountered that with Villiers, but they had the choice of the more obscure Brit threads, such as BSC [Brit Standard Cycle], its predecessor 'Cycle Engineers Institute', and of course BSB [Brit Standard Brass].
Wouldn't surprise me if they used a few of those here and there; they certainly did use BSC on engines.
A few machine manufacturers deliberately used only proprietary threads - Singer sewing machines are probably the best-known example, in their older models. Engineers of old termed them 'SBC' threads - Singer Bastard Cross!
And Enfield - your mention of them reminds me of the Royal Small Arms Factory, Enfield, who were notorious for using bastard threads. Have look at the listing
HERE.
They also used two different inch standards - the Enfield Inch and the Imperial Inch, which are 0.0003" different...
