*Crikey* Not another P8 Compass Question!

I’m approaching this forum in the hopes of finding out some relevant information on a P8 (variant) compass that I have in my possession.

A dear old British friend of mine here in Canada, who’s since passed away, was exempt from military service during the Second World War because his work was considered vital to the War Effort.
But alas, in 1946 he was drafted into the RAF to fill the void of returning airmen.
His employment afterwards involved aerial mapping all over the world flying in surplus aircraft.
During the 1950’s, he was involved in the first aerial surveys of the North Sea oil fields, and was involved in the aviation industry up until his retirement.
I believe he immigrated to Canada in the late ’50’s.
And along his travels, he acquired quite a collection of “aeronautical items” that were heaped into his garage, including an …*ahem*… RADAR unit.

The compass in question was made for the RCAF by the Ontario Hughes Owen Co. with a serial number 9311/43.
It is in quite good shape, the paint is solid, the unpainted brass is in very good condition, and the bowl is still filled with alcohol with a small bubble in it.
The only faux pas is a crack on the bezel cover glass.

But what’s unique about it is that it has both the Type P8 and Type P11’s engraved on the rotating bezel ring.
On the underside of the bezel is the number 1/1449.

What I can’t figure out is where does it fit in during the upgrade period of the P8 to P8M to the P11?
Was it modified concurrently with the P8M, before or after the P8M?
Was this a common engraving on some of the updated P8’s, or was it a unique interim measure to validate the upgrade until the “proper” covers were available?
And if the latter is the case and it’s so incredibly rare and sought after, should I be making a deposit on a private Caribbean island that I have my eye on for retirement?

But speaking of the bezel cover glass, I wonder if it’s “glass” at all or perhaps a type of polycarbonate (i.e. Lucite, Lexan)?
Rubbing my fingernail across it, it has more of a plastic texture to it.
Tapping it with a small screwdriver, it sounds more “plastic” than “glass” like.

I’ve attached several JPEG photographs for your perusal.

I truly appreciate any and all time the members here have spent on these inquires of mine.

Cheers!