I believe it's an English sporting rifle made up on an 1895 Dutch/Rumanian Mannlicher action. It appears that the magazine has been altered to accept a detachable box; the scope would have interfered with the original clip loading system. All the great English makers produced similar rifles, most of them in 6.5X53R. Fifty years ago, I could have bought this gun's doppelganger for $125 at Navy Arms' retail store. It was well above my pay grade then...
I still want one!