Moffat didn’t have to use the Seventh Doctor and Bernice Summerfield for this story, but given that incarnation’s scheming nature, it works for a story where the Doctor manipulates people and events for a greater good, but it’s also because Moffat loves Paul Cornell’s work (Moffat was reportedly Cornell’s best man, there’s a character in Continuity Errors called Orcnell).
Paul Cornell and the New Adventures
Back in 1989 nearly every televised Doctor Who story had been novelised, and once the TV show had been cancelled, Virgin Publishing were given a licence to publish original novels. Noting that the audience for these books would be adults who had grown up with the series, the New Adventures line allowed writers to be more explicit in terms of sex, language and violence. They were advertised as being “Too broad and deep for the screen”.
For these (and latterly the BBC Books Range – which still has an archived FAQ page online) open submissions were encouraged. Peter Darvill-Evans, the first editor of the range, noted the desire and knowledge present in fanzines and had been encouraged by the fourth novel in the series – Timewyrm: Revelation by Paul Cornell.
Cornell’s novels helped shape the New Adventures line, telling stories that were adult in content without being brazenly childish (several novels, revelling in the freedom to describe sex and violence, gave the series a reputation for gratuitousness) and taking the Seventh Doctor’s characterisation as dark as it could go (writing the only good version of Ace’s departure so far) and adding new companion Bernice Summerfield (an archaeologist who is still appearing in Big Finish stories to this day).
Cornell also delved into the past, exploring past Doctors as they appeared in the Seventh’s mind, expanding background events in Inferno and Planet of the Spiders to the extent that some fans consider these additions canon. Russell T. Davies praised Timewyrm: Revelation, in the 2013 non-fiction tie-in The Vault, as follows: “Paul bloody Cornell gave us Doctor Who, but he made it real. I mean, real people, laid bare, exposing all their anger, passion, and, damn it, nobility.”
So you can see why Cornell was chosen to write Father’s Day for the 2005 series, and to adapt his 1995 New Adventure novel Human Nature for series three. A lot of what carried over from the New Adventures to the revived television seriesechoed the style and content of Cornell’s novels. While he was far from prolific in terms of TV scripts (moving into comics in his later career), he’s probably the most influential writer of Doctor Who in the Nineties.