Thank you all for the links and information. We are making headway into the history. I asked the owner if there were rebuild plates and he said no. The only other marking he found were these stamps. Do these mean anything to anyone?
As mentioned above the C number was C5552276, as shown on Key Card 28a, a full scan of the card is available from me, for 20 euro's, there are appx. 17 bikes on one card.
