Annie and Clarabel are Thomas' faithful coaches, whom he loves dearly and would never dream of being separated from them.

Annie and Clarabel both have seating accommodation for carrying passengers; Clarabel also has a brake compartment for luggage and a guard. The two coaches are nearly always seen coupled together, with Annie usually facing Thomas and Clarabel facing backwards.

Annie and Clarabel are respectful to all of the engines, but most of all Gordon and Thomas, whilst they respect Daisy least of all for insulting them and Henrietta. They show a kind and caring side to everyone on the whole railway. However, despite their kindness and sweetness, when needed they can be stern, especially Annie. For instance, they scolded Thomas for teasing Gordon after his accident, although they are no saints themselves. Once when Daisy was rude to them, they naughtily tricked her into thinking there was something wrong with her which caused confusion and delay. When Sir Topham Hatt found out he told them that two wrongs do not make a right and that he expected better from both of them. Annie and Clarabel are best friends, but like all friends, sometimes they fall out but always try to make things right in the end.