British lens for air photography

We suppose that it is English made lens based on the crown and focal lengths marked in inches.

Quite used condition. Diaphragm is stuck. So, the lens needs servicing.

REF. ¹14À /843

It is a lens issued by the British government's Air Ministry, possibly for use during the Second World war 1939-1945, as I've noticed the reference numbers on other equipment for air photography of that period also starts with '14A', for example I have 16mm cine gun-cameras used in Spitfire & Hurrican fighter aircraft wings that start '14A'. Your lens may have been for use on large roll-film cameras, taking photos from the air of ground targets? 5" equals 127mm focal-length. It could have been issued in the 8th month August of 1943. (thanks to Martin Stent for this info).