Do any readers have philatelic expertise?

Or know anyone who does?

The item in the image above has me baffled.  I know with 100% certainty that it's not a postage stamp, a revenue, or a cut square from postal stationery, but I don't know what it is.

The corner letters are highly reminiscent of early British postage stamps, such as the Penny Black and Penny Reds.  The scrollwork in the bottom half is an elaborate "VR", which would certainly be "Victoria Regina" (Queen Victoria) - again suggesting 19th century Great Britain (or a British colony such as Australia/New Zealand).  Same with the crown.

But what is it?  The margins show partial frames of two adjacent items to the left and below, suggesting that it was cut and torn from a non-perforated sheet of presumably similar items.  The engraving is high quality, the paper is crisp and seemingly unwatermarked.  On the back is a hinge remnant, indicating that some philatelist had mounted it in an album.

It could be a simple "label" created for decorative or recreational purposes, or a "cinderella."  But I think it might be a die proof which was not successful in later becoming a stamp.

I'd welcome any insights from readers.

Addendum:  Andrew came up with the answer immediately.  See his comment.