I'm not sure if this is related, but who are/were "Magnalite England" who made the lights and lenses on the C5? I've noticed them on a lot of vintage lights but can't find a company history or website! Anyone know anything about them?
A quick Google shows it as 'dissolved'
http://companycheck.co.uk/search/results?SearchCompaniesForm[name]=magnalite&yt0.x=0&yt0.y=0
You're good. I wonder what became of all their moulds!