Millie is Sir Robert Norramby's prívate steam engine.
- Take-n-Play version (uni-polar magnets, red bufferbeam) (2013-2014)
- Take-n-Play version (bi-polar magnets, gold bufferbeam, longer in length) (2015-2016)
- Adventures version (hook and loop couplings) (2017-present)
- Millie's Dusty Discovery (Take-n-Play)
- The 2013 prototype Take-n-Play Millie has a yellow running board, buffers and boiler stripes, larger wheels, and lacks the Ulfstead Castle logo.
- The 2013 packaging features a special King of the Railway design.