It’s almost too easy to point out that travelling with the Doctor changes people. Considering that the overwhelming majority of companions come from the same time era as the audience watching the show, and that we humans have as yet failed to travel very far into space, much less nip across time or create an actual TARDIS, it’s bound to fiddle with your horizons a bit.
So when a public school student, even one whose tutor is the former Brigadier Lethbridge-Stewart, accepts a lift with the Fifth Doctor, you’d imagine his tiny mind would be blown out of his ears.
The interesting thing is it wasn’t. Turlough – played by Mark Strickson – appeared to have some knowledge of the ship and what it could do, and on a technical level beyond that of the Brigadier’s understanding. And for the first time there appeared to be a TARDIS traveller who had a hidden agenda. We found out there was something going on between Turlough and the Black Guardian, something to do with an offer of a return home (somewhere beyond the grounds of his former school) in exchange for killing the Doctor. In the meantime, he cuckooed his way in, and loftily prepared to betray his host at the first opportunity.
So, straight away we’re departing from the bored-but-sparky template from which so many of the companions have been minted. He’s a man with a dark past.
Here he is, playing both ends against the middle in the piratical romp Enlightenment. Everything you need to know about Early Turlough: The Rotter Years is shown here.
Despite being a turncoat and a weasel, despite all the scheming and selfishness, the profound change the Doctor makes in his life is to convince him to do the right thing. And it’s not one he’s entirely comfortable with at first. But he turns out to be more than capable of helping out in a tight spot. He can even assist with repairs on the TARDIS, and sends it to fetch the Doctor at the end of Planet Of Fire.
That’s also the story in which it is officially revealed that Turlough, whose first name is Vislor, is not from the home counties. He’s a political exile from the planet Trion. His reward for trusting the Doctor and changing his ways is to be allowed to return home as something of a hero.
The other side of Turlough’s time in the TARDIS is that he became less interesting the nicer he got. As his story of betrayal and deception wound down, and with no chance of him developing a Rory-style relationship with either Tegan or, latterly, Peri, he found himself in the classic companion position, being the one who gets captured. And seeing as Peri was clearly going to be much better at the job, what with all that screaming, maybe it was right that he went when he did.
And if Turlough’s story is one of redemption, it’s almost accidental. A case of the Doctor meddling with affairs without always being 100% sure that he’s doing it. Which suggests that his alchemical charisma runs bone deep.