Romana (as played by Mary Tamm) arrived in the middle of that period of upheaval in the role of the female companion which started with scientific Liz Shaw and ended with shouty Tegan. She was conceived as a character who would provide a touch of academic cool (and sophistication) after the more athletic charms of Leela. And for the first time since Susan, she would be another Gallifreyan, someone for whom the idea of a box which is bigger on the inside wasn’t immediately bizarre, and a potential equal to the Doctor.

Just like the female Russian agent in a James Bond movie, who has been reluctantly assigned to look after 007, Romana’s job, initially at least, is to keep her wayward companion’s mind on the task in hand. She’s prissy, a college graduate, and doesn’t immediately see why this strange fellow with the silly scarf has been trusted with the job of finding the Key.

But, as anyone who has ever seen a buddy movie knows, her fancy book learning doesn’t answer every question, and his intuitive approach, based on years of experience in the field, is not something to be dismissed lightly. So they soon start working as a team.

Here’s how the whole Key To Time thing got started, and Romana I’s first appearance.

http://www.youtube.com/watch?v=ExQFoiFHt0I

Oh look, the Doctor is bickering in the TARDIS with his companion. How novel!

Eventually, of course, the job got done. The Key to Time is found, and the Doctor, worrying that he’s got a source of ultimate power in the TARDIS, installs a device to keep them away from the Black Guardian, and resume his old travelling ways.

It’s at this point that Mary Tamm decided to leave the show, apparently because she felt that the equal footing Romana was supposed to share with the Doctor had become weakened, and that she was just another corridor-running companion. Here’s her last scene:

http://www.youtube.com/watch?v=gep2IObhqKk&feature=related

Thankfully, the Doctor Who production team had an inventive solution to this problem. If Romana is Gallifreyan, she can regenerate, so why doesn’t she? Never mind all that mucking about with life and death, and illness, Romana II (played by Lalla Ward) regenerates like she’s picking out a new hat:

http://www.youtube.com/watch?v=xT99o3SyVkM

It’s at this point that the thaw between the two time travellers is complete, and their relationship becomes very affectionate. Romana II is considerably less prim than her previous incarnation, and easily matches the Doctor in terms of playfulness and ability. The fact that Tom Baker and Lalla Ward were in the middle of a relationship too (they were married for a while) probably helped. Naturally, this is going to lead people to put two and two together:

But in the end, the Doctor, particularly the Fourth Doctor, is still far to caught up in himself and his lifestyle to even consider that he might have an equal. His demeanour, even when at his most intimate, is always that of energetic and friendly schoolteacher, who knows his pupils will leave at the end of the year and get on with their lives. Not that Romana is much different in this regard, she even dresses like a schoolgirl at times. She learns a lot from the Doctor and then, shortly after Gallifrey ask for her back, and while they’re stuck in E-Space, she simply walks off with the minimum of heartbreak.

So even though there’s a lot of friendly chemistry between the two of them, there’s no heat. Not even a trace. They don’t even really NEED to stay in each other’s company. These weren’t star-crossed lovers pulled apart by fate, they’re best friends who met while working on a job together, and are content to go their separate ways, maybe sending the odd card now and again, depending on how sentimental their regenerated selves are feeling.

Here’s her final farewell. Is the Doctor’s parting shot a dig at Romana I?

Next: Adric, a mathematician in pyjamas.