If asked, Christina would say she rescued Romana from Torchwood. Actually, that's a lie, she'd say she stole Romana from Torchwood. Romana would say she was escaping anyway and just happened to run into a human in possession of a flying bus on the way out.

This was going to be the subject of many future disagreements.

"Christina de Souza," she introduced herself once they were back on the bus, "Lady Christina, actually."

"My name is Lady Romanadvoratrelundar, but you can call me Romana if you like."

"Yes, I think perhaps I'd better."

"Time agent?"

"Excuse me?"

"Apparently not. I just assumed on account of the flying bus, it's just about ostentatious enough for one of them. Well," Romana said, taking a step towards Christina and looking her up and down, "you look human."

"You look Time Lord," Christina replied automatically.

Romana was pale anyway, but what little colour there was drained from her face. "What did you just say?"

"The last alien I met, and I'm assuming you are an alien and that Torchwood doesn't imprison humans on an island in the middle of the English channel for failure to pay inheritance tax, he was a Time Lord."

"The Doctor." It wasn't a question.

"You know him too. He does get about, doesn't he?"

"I assume he's the one who provided you with this flying anachronism?" The bus was hovering over the water.

"He built it, yes. Then I had something of a misunderstanding with Scotland Yard and it was just sitting there, so I borrowed it."

"A misunderstanding?" Romana asked with a smile.

"I have an interest in certain historical artefacts."

"What form does this interest take?"

"I steal them."

"I can see how that would lead to misunderstandings." Romana looked at her surroundings. "I don't usually make a habit of stating the obvious, but isn't a flying bus a somewhat conspicuous method of transport for someone laying low from the authorities?"

"That's why I'm here," Christina admitted. "I heard a rumour that Torchwood might be storing something here that could help me be a little less... conspicuous. Unfortunately, you setting off all those alarms meant that I didn't get a chance to look around properly."

"It's lucky that you met me, then." Romana proceeded to produce what looked like an entire spaceship reduced to its component parts from the pockets of her coat.

Christina exhaled, and her face broke into a wide smile. "Remind me to get a coat like that," she said.

Romana had liberated everything needed to construct a spacecraft from scratch from the Torchwood facility, but it would take quite a while and involve more welding than she felt was really dignified or presidential. If she used the bus as a base, it would take only a few hours.

"Lady Christina, have you ever wanted to see the stars?"

"It's funny that you should mention that."

Romana looked at the penguin. The penguin looked back. She cocked her head to the side; the penguin did the same. "You know," she confided, "I'm really starting to distrust her driving skills."

"There is nothing wrong with my driving, thank you very much," Christina said, hopping off the bus.

"And that's why you've landed us in the penguin enclosure at Edinburgh zoo, is it?" asked Romana.

"That's parking," said Christina, "I've always had difficulty with parking. You wouldn't believe how many tickets I've got."

Romana sighed, regretting discontinuing her conversation with the king penguin.

"And you said we needed to land to finish work on the bus," Christina pointed out.

Two hours later, just as dawn was breaking, a slightly dented double decker bus lifted off from the island in the middle of the penguin enclosure. It hovered fifteen feet in the air and there was the sound of grinding metal, as though the space-time vortex was saying that one flying bus was quite enough, thank you. Then, with a flash of light, the bus vanished.

The penguin looked on impassively. This planet really was going to the dogs. First global warming and the decline of fish stocks, then Daleks everywhere and now humans opening a portal into the space-time vortex in the middle of the enclosure without so much as a by your leave.

Romana leaned against the side of the bus and watched Christina strap herself into the elaborate harness. Christina attached one end of a length of rope to the harness and clipped the other end to the front of the bus. She walked smartly to the ledge of the roof, turned to Romana and asked, "Are you sure you won't join me?"

"Quite sure."

"In that case, I'll be back later." And with that, Christina leaped backwards off the roof.

For a few moments Romana watched Christina rappel down the side of the skyscraper they'd landed on, then she went back to the bus, started the engine and reversed the three feet necessary to reveal the trapdoor on the roof. She used her sonic screwdriver to open it and headed down to surprise Christina on the ground floor.

Their first trip to another planet didn't end brilliantly. In fact, it ended with them both locked up in a prison cell and Christina trying to break them out with a lock-pick she'd had strapped somewhere indecent.

"It's your fault," Christina said, venting her frustration at the lock on Romana.

"How do you come to that conclusion?"

"The revolution wouldn't have succeeded if it hadn't been for you."

"I know, I'm very good at revolutions. And it's hardly my fault that you were on the losing side." Christina groaned when her lock-pick snapped in half in the lock. "Oh, let me do it." Romana pointed her sonic screwdriver at the lock and the door swung open.

"I really must get myself one of those," Christina said wistfully as Romana strode past.

Their visit to Queen Elizabeth's court got off to a marvellous start. Well, it did once Romana had explained that one, she wasn't the Doctor in a new body, and two, she no longer had any responsibility for the Doctor. It ended less auspiciously, with the Queen's guards pursuing them back to the bus and Christina reversing through the wall of the Globe Theatre, executing the universe's quickest three-point turn.

"Must you wear that thing?" Romana asked. Christina was steering the bus while wearing Queen Elizabeth's crown.

"You're right." Christina reached back and dropped the crown onto Romana's head, it slipped down her forehead and covered her eyes. "Maybe not."

"Why don't you just concentrate on driving for the moment?" Romana slipped the crown into the coat pocket she reserved for Things Christina Has Stolen That Will Have To Be Returned Next Time We're Passing That Way.

The Cybermen had once had a traumatic experience with Iris Wildthyme. As a result of this, their immediate reaction to the sudden arrival of a red double decker bus was to abandon their attempt to take over the Earth and concentrate on deleting the bus and its occupants.

Romana reached into her pocket for the sonic screwdriver to deactivate the Cyberman that was advancing upon her, but she came up empty handed.

She smiled brightly at the Cyberman. "A quick word of advice, if you ever find yourself travelling the universe with a kleptomaniac keep a close eye on your ."

Romana was just about to come up with a plan B when Christina dropped the bus to the ground from a height of fifty feet, smashing the Cyberman and probably irreparably damaging their suspension.

"What would you do without me?" Christina said, opening the doors. As there were Cybermen everywhere, Romana didn't feel it was really the time to get into that conversation.

After the Cybermen had been dispatched, Christina and Romana were wandering the streets of London in search of a twenty-four hour garage that supplied spare parts for double decker buses.

"Hey," Christina caught hold of Romana's arm. "Little blue box."

Romana looked in the direction Christina was gesturing. There stood the familiar blue police box. "Christina, I'm going to need that sonic screwdriver you stole from me back."

"What are you going to do?" Christina asked, casually handing the screwdriver back.

"I'm going to ignore everything I've ever said to you about making off with other people's property."