Millie is Sir Robert Norramby's private French steam engine.
Millie is based on Decauville 0-4-0 well tank No. 8069 "Tabamar", built in 1911. Unlike her basis, Millie has a rear coal bunker.
Millie is painted French blue with white lining, a golden running board, boiler bands and wheel spokes, Sir Robert Norramby's crest on her cab sides and her name painted in white on the sides of her tank.