Lee Enfield 1955 Fazakerly Production - Strange Marking...

Hello Gents,
A few months ago I picked up a new unissued, still in cosmoline No4 Mk2. In the process of disassembly and cleaning I found a piece of paper with an"O" on it stuck to the top of the barrel near where the barrel comes into the receiver. Strangest thing...
I have no idea what it may mean but figured I would pass a photo along to you and perhaps it rings a bell for someone. I would appreaciate any help understanding what this is all about.
Thanks for your help. Keith aka chambekAttachment 94669