In the late 1960s and early 1970s British tanks were equipped with infrared detection systems that alerted the commander if his tank was lit up by an IR system. The system consisted of a ‘stalk’ by the cupola that sounded an alarm inside when IR hit it. These systems obviously needed to be checked to ensure they were working correctly, so the REME were issued with specialist testing equipment:

This is a metal, handheld device, with a control knob, light bulb and two terminals beneath the carry handle:

The batteries are stored behind the control panel and require screws to be removed to allow access:

The front half of the device has a pair of spring clips to hold it on and a hole in the top, presumably to fit over the IR detection stalk:

A hole inside this front housing conects it to the rest of the device:

A removable red plastic plate slides in between:

The tester has a small data plate attached to it that gives its description and an NSN number:

The IR detection system was fiddly to use in practice and some commanders claimed that the sensitivity could be set to allow the alarm to go off at day break!