Original 1942 WW II British Mark III 2024 Prismatic Marching Compass by T. G. & Co., London

Original 1942 WW II British Mark III Prismatic Marching Compass by T. G. & Co., London
It is made of solid brass.
This is not an imitation piece but one that was actually used in WWII.
There are signs of wear on it. The dial has a patch of discolouration on the periphery. I am not an expert in the use of military compasses and I do not know how this may have affected its functionality. The inscribed information at the back has partially rubbed off.
Kindly see pictures carefully. 2024