So, how much of The Ark made it into The Ark in Space? “Robert Holmes wasn’t rewriting it at all – he was writing a new script from scratch,” says Jonathan Morris. “Hardly anything of Lucarotti’s script ended up in The Ark in Space, but there are some similarities – the setting, obviously, and the idea of people being possessed by an alien force, something which hadn’t really happened in the Barry Letts era but which would become a big part of the Hinchcliffe era. The set-pieces of our heroes running out of air and Sarah crawling through ducting are there, and there’s a line about a dust extractor which seems to be an inadvertent hangover.”