Anyone know: Can you use an Armed Forces "bluey" if you find one?

[r00fie1]

Wondered if anyone knows?
I found an old blank blue envelope amongst my souvenirs whilst clearing out the attic.

 

[Norfolkred1]

BFPO to BFPO is that's still around. Does it have a stamp on it, some used to be pre-paid.

 

[r00fie1]

BFPO to BFPO is that's still around. Does it have a stamp on it, some used to be pre-paid.

Pre-paid.
I dont want crap hats coming round in the middle of the night:eek: