Thanks for the response. Lens is the 10cm 2.9 Serial No 99829 (if that helps with dating it). The cold shoe is marked "Germany" and appears to be either nailed or riveted on. However some of the lens surface looks as though it's been 'polished' with 000 grade wire wool. . .
Just waiting on a film back to arrive, would be good to find out if the sync is 'new' enough for flash, or if it is for the older M flashbulbs. Any idea on how to replace the bellows, or how IR proof they are? Would be nice if there were a decent resource on these cameras.