In both versions, Chronotis is a clandestine time-traveller, whose time machine (or TARDIS, as they are termed in Doctor Who) is disguised as his college rooms.

In Shada, Chronotis is a retired Time Lord and old friend of the Doctor, living out his remaining centuries in academic seclusion.

Despite his innocence, the Time Lords attempted to imprison Salyavin in Shada for fear of him using his unique mind powers to take over Gallifrey.

Here Chronotis is so old and forgetful that he has no idea who or what he originally was, though he has vague memories of Cleopatra (who he claims wore outrageous earrings and reeked of cat food and death), and believes that he achieved his position after his retirement from "something pretty good".

His Chair of Chronology was created by mad king George III who was terrified that if time were to start flowing backwards, all the bad experiences of his life might recur.

In 2007, Dirk Gently's Holistic Detective Agency was adapted to radio and Professor Chronotis was portrayed by Andrew Sachs (who had previously played Skagra in the Big Finish audio/BBC webcast version of Shada).