A. N. G. L. OS/798 GA Rangefinder No12 MKVII. Used for distance measuring.
The rangefinder is stamped with the War Office ‘broad arrow’ (see top left of plate in Image 2). The top of the tripod stand is punched “P. B & S Ltd 19?2 1161 STAND INSI No14 MK III”.
For the tripod see https://ice-museum-scotland.hw.ac.uk/product/2000-003-1/.
Also present: Instructions for Use for similar Barr and Stroud rangefinder published by Research Enterprises Ltd, Leaside, Ontario, August 1941. This booklet is stamped “Thomas H Manson & Sons Ltd. / OPTICIANS & SCIENTIFIC INSTRUMENT MAKERS / 5 & 6 DAME ST. DUBLIN”