Photos: John Walker/Geoff Moxon

There were three Ground Guidance trailers used for the Corporal missile, a radar tracking vehicle, a doppler trailer and an analog computer flight predictor. These photos show the inside of the computer trailer, with its many rack-mounted chassis, and Cpls Bill Watkins and Geoff Moxon performing a routine calibration of a servo unit in Napier Barracks, probably in 1961.