I acquired my first double 62 years ago & haven't been without one since. Like Stan I can't recall ever having the need to open one upside down. "IF" in fact that spring had the force to flick them barrels up to open it with the gun upside down I think you would find it extremely hard to close. While my experience in actually handling & Closing a Purdey has been limited to exactly 1 I found it remarkedly smooth & easy to close (right side Up). I should have bought that one but at the time just didn't think i could afford it.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra