Correct, IIRC, all JBs were out shopped in the livery shown above. My point re the Bulleid was that no one would tolerate a post war built loco, such as a West Country or a Battle of Britain, running in Southern Olive Green because they never did. So why should a diesel be painted in green, when they ran in rail blue from the start. It is amazing how some railway enthusiasts seem to conveniently forget that for three years there were rail blue diesels, electrics, EDs such as the JB, multiple units, together with some blue and grey coaches running around with steam locos, at the end of steam.
https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjJibOEvJf-AhXbh1wKHQG9D1UQtwJ6BAgiEAI&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dqruu7-k27P0&usg=AOvVaw0clIUZqB1EulX3qX5GvjZ3
Railways didn’t end when steam finished. That JB lasted so many years longer in main line use than most steam locos ever did.