Conditions of use
The "David Agnew" pseudonym was most-often used when the original freelance scriptwriter was unable to accommodate fundamental changes requested by the production staff, and the production staff had to perform a major, last-minute rewrite themselves. BBC rules prevented the production staff from taking screen credit without a time-consuming, bureaucratic appeals process, meaning that the quickest way for the project to continue under the BBC system was to use the name of a non-existent writer. Sometimes production staffs were directly ordered by BBC management to use the credit.
Unlike the similar "Alan Smithee" credit for film directors, "Agnew" was not used in protest of the finished product. Indeed, the actual writers of a "David Agnew script" — typically the producer, director and/or script editor — would ideally liked to have received credit for their work, had BBC rules permitted it.
The name seems to date to 1971, when Anthony Read's script for the Play for Today episode "Hell's Angel" was broadcast under the pseudonym. Read's work on the 1975 BBC2 Playhouse episode "Diane" was likewise credited to "David Agnew".
The pseudonym entered into use on Doctor Who only after Read had become that show's script editor. Read and producer Graham Williams used the pen name hurriedly to assemble The Invasion of Time in 1978. A year later the name concealed the joint work of Douglas Adams, Williams and David Fisher on City of Death.
The name was also used for the episode "Blow Out" of Target. In this case, a two-hour script was pared down to one. Writer Roger Marshall quit at the pre-production stage, leaving director Douglas Camfield to, as Marshall said in an interview, "butcher" and "doctor" it.
Use outside television
While the practice of using the pseudonym on television was exclusive to the BBC of the 1970s, it has worked its way into Doctor Who fandom to a certain degree. In March 2000 "David Agnew" was used for a Doctor Who book, the short story anthology Short Trips and Sidesteps, in homage to the pseudonym's use on the television series. Agnew was also the subject of a The Elusive David Agnew mockumentary directed by "Allen Smithee" on the DVD release of The Invasion of Time. A character in the 2013 Doctor Who short novel The Death Pit, by A. L. Kennedy, is named David Agnew. Loose Cannon's Dailymotion username is DavidAgnew 
- Sullivan, Shannon (29 August 2008). "City of Death". ShannonSullivan.com. Retrieved 25 February 2009.
- Sullivan, Shannon (8 June 2008). "The Invasion of Time". ShannonSullivan.com. Retrieved 25 February 2009.
- Rolinson, Dave; Williams, John (eds.). "Play for Today Episode List Part 1: 1970-76". The University of Hull. Archived from the original on 5 March 2007. Retrieved 25 February 2009.
- "Full cast and crew for "Play for Today": Hell's Angel". IMDb.com. Retrieved 25 February 2009.
- "Full cast and crew for "BBC2 Playhouse": Diane". IMDb.com. Retrieved 25 February 2009.
- "Target". Media Gems. Retrieved 24 February 2009.