In Nov. '58 one Class 116 set was fitted with final drives having a lower gear ratio than standard to assist operation on the steeply graded eastern valley services out of Newport. The set, CAT404 W50086/W59036/W50128 could not operate in multiple with the standard units and as a consequence it’s blue square coupling code was given an additional mark in the form of a cream diagonal bar to indicate this to operating staff. It was restricted to 55mph.

Dedicated to these services until the closure of the eastern valley network to passenger services, on the 30th April 1962 the low ratio gearing on this set was later returned to standard.