Class 31 No.31018 in the standard Rail Blue colour scheme

It was decided in 1965 to standardise the BR colours which became known as Rail Blue. Also known as "Monastral Blue", It was a dark, greyish blue tone which hid the effects of dirt well. The colour often appears inaccurately in photographs, generally appearing brighter and bluer than the real colour.

          In the early years the colour faded quite badly, becoming lighter and paler with time although this problem had been overcome by the late 1970s. United Kingdom paint "Ocean Blue" is a good match to Rail Blue.

The new British Rail "double arrow" symbol were appled to the  locomotives and the vehicle number and other ancillary markings were written in the Rail Alphabet typeface

          The colour was applied to all the diesel and electric locomotives, with the exception of the ends, which were painted yellow to improve visibility, and the underframes and buffer beams which were painted black; As Rail Blue was introduced, the last locomotive recorded  were  being outshopped in a previous livery the  Class 43  Rapid which left Swindon Works in August 1968 in maroon.