Two brand new Class 312 GE outer suburban EMUs led by 312106 on 24 March 1976 at Colchester. The headcode 5Z74 and the word Special on the train indicator suggests they were on trial. The 312s were developed from the successful AM10 units used on the London Midland Region, the main distinguishing feature being the flat windscreens instead of the wrap-around type on the earlier LMR sets.