William Tiddler

In the novel The Mirror Crack'd from Side to Side, William Tiddler is a Sergeant who assists Craddock. They call him Tom Tiddler, from the children's game. Inspector Craddock chooses Sergeant Tiddler to assist him because he is a good man, and is also a film star. This allows him to be at ease with the film actors.

Sergeant Tiddler is sent to the studios, and returns with the report that there is not much gossip and no startling rumours about the case. He says that there were no rumours about Jason Rudd being involved with another woman, or Marina Gregg being involved with another man. There were also no rumours that Jason might have been responsible for poisoning Marina's glass. They both seemed to be devoted to each other.

Sergeant Tiddler is later sent to The Development, to question Gladys Dixon. However, he is told that Gladys had gone for a holiday, and had not left an address.

Portrayals
Sergeant Tiddler does not appear in BBC's 1992 adaptation of the novel. There he is replaced by the series recurrent character Detective Sergeant Lake.

In ITV's 2010 adaptation of the novel, the part of Sergeant Tiddler is played by Samuel Barnett. He is a fan of Marina Gregg and is able to supply his superior Inspector Hewitt with important background information from time to time.