Here’s Christopher Priest talking about his brush with ‘Doctor Who’ in the late 70′s and early 80′s. He wrote two scripts, neither of which ended up getting made, and apparently ended up in a major argument with John Nathan-Turner and Eric Saward:
“I’ll take on almost any writing job, provided it sounds interesting. Doctor Who was like that. The programme is a challenge to a writer: a tiny budget, a more or less fixed cast of characters, a fairly inflexible storyline … and millions of fans who’ll beat the shit out of you if you overlook a crucial fact mentioned in an undertone by a minor character in the second part of a story first transmitted in 1968…
“I wrote two scripts. The first was while Douglas Adams was script editor, before the Hitchhiker books burst on the world. Douglas rang me up one day and said the producer felt the show was drifting away from the heartland of sf, and wanted some ‘real’ sf writers involved. I went in and met Douglas, and he commissioned a four-parter called ‘Sealed Orders’. I wrote this, and it was accepted but never produced. This was because of upheavals in the show while I was writing. Douglas Adams pissed off to become rich and famous, the producer also moved on, and by the time I delivered my story the ‘brief’ (the background story) had changed.
“The BBC commissioned a second story called ‘The Enemy Within’, because of the first going wrong. Again it was written and paid for, but once again upheavals in the BBC wreaked havoc. They inflicted a total of three different script editors on me, who all mucked around with the story and demanded different things … and the new producer [John Nathan-Turner] turned out to be an appalling little [censored by original interviewer], who was more interested in being a media star than actually working with a lowly writer like me. It all led inevitably to a bust-up. I grabbed a parachute and took a header through the nearest emergency hatch.”
You can (and definitely should) read the full interview here, it goes into a lot more detail about his career.