Sidney is a kind, but forgetful blue diesel shunter from the Island Of Sodor.
Sidney is a friendly but constantly bungling diesel. This isn't so much because of clumsiness however... it's because Sidney is a very forgetful engine! Thus, he often leaves with a train and forgets where to go with it!
Sidney is based on a BR Class 08 diesel-electric shunter. Over seventy members of this class survive today in preservation, while around 100 remain in service on the national rail network. They were in fact the most successful shunting engines in the world, with a total 996 of them built. Diesel, Splatter, Dodge, 'Arry, Bert, and Ruth are also members of this class.
Sidney is painted blue with yellow lining, red siderods, and black wheels.