The Diesel was snobbish and rude, believing that diesel engines should take over from steam engines.
When he visited Sodor, D261 was painted in the BR Brunswick green livery, with a thin, lighter green stripe running along his top and yellow warning panels. The number "D261" was painted on his cab sides in yellow.
At some point after returning to British Railways, he was repainted into the "Rail Blue" livery. He had the BR logo painted on his cab sides, and the number "40 061" painted on opposite in white.