First: I have neither affiliation to nor any appreciation for the seller. I have purchased from him long ago and had good service.
Second: I know he has access to items made by the former manufacturer Overhoff & Cie. (Overhoff has been sold, has a new company name (but the original OLC <in diamond> logo.
Third: Many buttons on offer are thin metal restrikes from original designs. I do not know if 'production' has continued or that Overhoff itself produced buttons from old dies.
Fourth: I know German manufacturers managed to get Britisch button contracts c.1980s.
Here are his badges:
http://www.ebay.de/sch/m.html?_odkw=...anien&_sacat=0
If not genuine, then badge collectors have another resource for identifying fakes.