RAF Sunglasses, are models listed anywhere?

[Rabaul]

Hi All, Have just bought a pair of Air Ministry sunglasses, made by Levers. The case has -

A*M
294/11/P/2295
LEVERS.

Of course * is a crown and 'P' might be an 'R'

I can find very little information about these sunglasses, they are not covered in Proger's book and searches just bring up a few 'for sale' pairs with brief vendor discriptions.

Can anyone tell me something of their history? Adoption date, designation, uses etc?

Some vendors say these were pre-war, and there seem to be several post-war versions. Is there any where with a clear listing of RAF sunglass types?


All the best

Steve