Dr Enfield is a police doctor used by the Borders & Lothian Police. In Hide & Seek, he is called out to examine the body of Ronnie McGrath. That night he performs a post mortem, and discovers that the cause of death was some 95% impure heroine injected by Mr McGrath. The next day he informs John Rebus his findings.
Dr Enfield was named after Richard Enfield, a character in The Strange Case of Dr Jekyll and Mr Hyde.