I know little about this target set as there is no makers name anywhere to be found
Probably circa 1950s
John has provided me with more information
"This is a CTS /Vickers item. The paintwork is that used on the Tavistock Mk II and the S series of levels. Although CTS went through a number of paint finishes including battleship grey, a smooth greeny-gray shade, the shade on the target and latterly orange. The paintwork would be a very rough indication of age. The position of the optical plummet telescope halfway up the pillar, the 90 deg"V" configuration of the long bubbles at the base of this central upright, the retaining knob & its housing on the tribrach and if you remove the target from the tribrach the clamping mechanism pushes the centring flange against two proud stops.This forced centering tribrach was peculiar to the York company."