Dicks was born in 1935 in East Ham, Essex, and studied English at college. He did a stint in the British Army on National Service, and then worked as an advertising copywriter. The need to produce a large amount of written material to strict deadlines later served him in good stead as a scriptwriter and novelist. He started writing radio plays for the BBC in the late 1950s and in 1962 was recruited by his good friend Malcolm Hulke to co-write episodes of the drama series The Avengers.
His association with Doctor Who began in 1968 when he was recruited to serve as script editor during the third and final season featuring the Second Doctor, Patrick Troughton. Dicks and Hulke re-teamed to co-write the epic ten-episode saga that concluded Troughton's run, The War Games. Dicks and incoming producer Barry Letts also masterminded the first major shift in Doctor Who's format, which saw the show switch to colour production and introduced UNIT.
Dicks and Letts formed a highly successful "dream team" which oversaw all five seasons of the Third Doctor, Jon Pertwee, and introduced the Fourth, Tom Baker. This period is one of the most critically acclaimed of the show's run. Dicks didn't accept any writing credits during this period, despite sometimes heavily rewriting scripts from other writers. Dicks also became something of an expert on the show's history and canon, writing the 1972 non-fiction book The Making of Doctor Who.
He stepped down as script editor during the Fourth Doctor's first season and resumed writing scripts as a writer on the show, turning in Robot (Tom Baker's first story), The Brain of Morbius, Horror of Fang Rock and State of Decay. In 1983 Dicks' knowledge of the history of the show led him to be invited to write The Five Doctors, the Doctor Who 20th anniversary special. This was Dicks' last on-screen contribution to the Doctor Who mythos, having penned 35 episodes in total.
The net result was that between 1974 and 1990 Dicks would write 64 novels. His most productive year was 1980, when he published no less than nine novelisations. This novels were short by modern standards - typically 120-124 pages - and of course were based on pre-existing scripts, but this was still a hugely impressive feat.
It would not be an exaggeration to say that Dicks taught an entire generation of British children to read: the Target Doctor Who range sold enormously well for over twenty years and Dicks was by far its most productive author.
In the 1990s Dicks switched to the Doctor Who: The New Adventures line which told new and original stories. Dicks' first novel for the line (and the second in its run), Timewyrm: Exodus, was also one of the most critically-acclaimed, a dark and edgy story set in an alternate timeline where 1950s Britain has lost WWII and is under Nazi rule. The brutal and adult story set the tone for the line (especially after the disappointing opening book). Dicks contributed several further, well-received books including Blood Harvest (a sequel to his TV script State of Decay). He switched to the BBC Books range when they reacquired the licence in 1996 and he wrote The Eight Doctors (1997), the biggest-selling Doctor Who novel of all time. His last contribution to the novel range was Revenge of the Judoon (2008), featuring the Tenth Doctor.
On top of all of that, Dicks also wrote the two official Doctor Who stage plays (Seven Days to Doomsday and The Ultimate Adventure) and two fan movies (Shakedown: Return of the Sontarans and Mindgame).
Outside of Doctor Who, Dicks wrote scripts for Moonbase 3 and Space: 1999, produced the mini-series David Copperfield and The Diary of Ann Frank and wrote no less than 143 other children's books and YA novels.
Terrance Dicks was the most prolific writer of Doctor Who, but also a generous writer known for bringing other talented writers onto the franchise. He will be hugely missed, especially by those of us who still have a box of his Doctor Who novels under the bed.