Howard, Simon,
as Brückenheim (IIRC) is based in the Mittelgebirge, specifically Eifel, there would not have been any netting. At least I can not recall seeing any in the seventies and eighties.
Most of the area's rock is hard rock (no punning: I mean the hard rock that bangs one's head and not the hard rock one's head bangs to...).
Best Regards,
Christian