Taken from French website and with Google's translating software, then translating that-here's what we could figure out about the elusive Condor.
"Seeley was founded at the end of the Sixties by racer Colin Seeley. They repurchased the patents of two machines Matchless (G50) and AJS (7R). They developed the G50, a 50cc of ultra race powerful which gained all brilliantly them They later produced of it a version of road which it baptized “Condor”. A few years later they built cafe racers using base existing engines, in particular that of the CB750 Honda."Update: Here's The Seeley Honda Register's Description of the bikes:
"The Seeley Honda consists of a Honda 750 SOHC/4 engine in a custom chassis built by Colin Seeley, UK. 302 Seeley Honda chassis were built by Colin Seeley between May 1975 and sometime in 1978. Some of them may have disappeared, but the majority is still around. It is the goal of this web site to put together a register of all those Seeley Hondas which are missing in action, stored away somewhere, under restoration or still alive on the road.
There were four different versions of the Seeley chassis: One for the CB 750 K models (actually only for K0 up to K6), one for the F1 Supersport model (and the K7/K8) and one for the F2/F3 Supersport. Then there were the racing chassis which had a special oil tank and some other minor modifications. Frames for the German market had different steering locks and stops."