Several detectors, at the rear, from left to right:

Made by G.E.C. London, Witton & Manchester  England.

Silvertown 1916, table top detector galvanometer .

Table top differential detector galvanometer marked: “P.R.E.W. 1916”.

Detector made by Henley London.

Front row, from left to right:

Intensity and quantity detector (I & Q) made by Edison & Swan, No.26400 1919.

G.P.O. detector (I &Q)  with switch to change shunt coil from Full to 1/5 Shunt.

Unmarked I & Q detector galvanometer.