Another worthy European (Netherland) contender: Golden Earring: Eight Miles High.
Maybe Procol Harum, on Home, isn't quite prog. Like many bands they tried to sell records - become more commercial. But often, it did not hurt.
Same thing with Steppenwolf. On their 7 album, tracks like Renegade and Hippo stomp carry their bluesrock into prog territorry. Not much recognized, in the prog camp.
And - Yes: close to the edge rewards a new listen - but this british side of the prog story is only some of it. And somewhat tiring, now, to my ears.