It's either an automatic, or a straight-pull bolt-action. It does not look like the handle can rotate at all (just reciprocate), but the bolt seems designed to rotate to lock. The hands holding it (right hand holding the charging handle, seemingly back against spring tension, left hand forward, holding the rifle) are gloved, so I'm going to go with "rare, valuable, and not owned by Ian". Ian has very thoughtfully cropped the photo, so you cannot tell if there are peep sights to the rear of the rifle, but I'm going to guess not...seems a bit long of a section to the rear of the action to then have sights mounted out of view to the left. That means a barrel mounted sight, which spells "military" to me. However, the size is small (.22?) and no charger guide. There is wood covering the barrel (upper handguard?), which also says "military". There is a projection on the left of the receiver (above the receiver in the photo) that looks mauserish to me. There is a metal magazine visible on the bottom, but no charger guide? Hmm.
Does it take en blocs? Was there some semi-auto developed from the M95 Steyr, or something similar to it?
Mike