"Would you like to write a new Doctor Who story?"

Books Marcus Sedgwick has written a short piece for The Guardian about the process of writing The Spear of Destiny, Puffin Doctor Who e-book from last year. Here's how he got the commission:

Four days before Christmas, the phone call went like this:

Editor: Would you like to write a new Doctor Who story?
Me: You had me at "Would you like to write".
Editor: It's a crash schedule.
Me: Scare me.
Editor: You have four days to submit a synopsis.
Me: Ulp.
Editor: And a week to write it.
Me: *strange strangled duck like noise*
Editor: *hangs up*

About five minutes after that, the reality of what I had agreed to dawned on me. For a good few reasons, I was, well, let's say apprehensive.

Under this pressure he arguably wrote the best of the series, entirely in keeping with the Pertwee era, especially in the characterisation of the Doctor and Jo, paying homage to it and also trying something new.