A Most Singular Engine

A Most Singular Engine is an episode from the twenty-first season.

Characters

 * Thomas
 * Henry
 * Gordon
 * James
 * Percy
 * Harvey
 * Emily
 * Sidney
 * Den
 * Dart
 * Diesel 10
 * Diesel
 * Daisy
 * Ryan
 * 'Arry and Bert
 * Hugo
 * Philip
 * Judy and Jerome
 * Sir Topham Hatt
 * Duck (cameo)
 * Oliver (cameo)
 * Gina (cameo)
 * Whiff (cameo)
 * Trevor (cameo)
 * Jem Cole (cameo)