Thanks Ole. I was typing fast, but of course, anything that says 'doppel' instead of 'double' is likely to have 'Serie' instead of 'Series'.
I picked the lens up this afternoon. A beauty, and a beast. Fairly compact for a 480mm f8, but all that brass and glass adds up to nearly 2kg. It will make a fitting normal front end to my Optemus, and it gives me the incentive to sort out my film holders.
This one too has an iris (slightly wonky, but basically round) marked in what I assume are Stolz (Stoltz?) stops. The smallest stop is marked as something like '1400', which if it were a regular stop would be beyond even my tolerance for diffraction.