The April 1937 edition of AP1275 Volume 1 (published in 1939 for 7/6) gives this:

I don’t think it is Mk XIV (T1) Bombsight since the Roll gyro in the Sighting Head and the pitch Gyro in ther Computor both had mechanical output shafts that controlled the sighting glass in the Sighting Head and the interrupter blade in the computor. And the vacuum connection was next to the large air intake filter.

A quick experiment with MS Word seems to show that the font “gulim bold” and “gulimChe bold” are pretty good approximations.Not of course that your average printer can engrave placards!

More:

and three more to come

The piece in the helmet was (apparently) male and the female part connected to the microphone in the oxygen mask. The connection to the aircraft came out of the back of the helmet and connected via a “Jack Plug” to the aircraft. I hope these pictures help the explanation. These are probably later than 1945 though.

Here is my one in its cloth helmet. I had withdrawn it for the earlier photos. I would say it is a male as it has the pins and the microphone has a plug with two sockets, however the microphone “plug” has its sockets shroded in bakelite so that you might say it is a plug! See second image.

Its seems to be the microphone connector from a leather, or cloth, helmet:

Does this answer your query?