“€34 per person, per day….” Marion said thoughtfully. “What’s that in sterling?”

“£30.92, rounded to the nearest whole penny, at today’s exchange rate,” Kristoph answered instantly, without having to refer to any conversion chart. “Would you like it in Gallifreyan cressits, too?”

“No, thanks. I’ve never really worked that out against Earth currencies, since we don't actually have any trade agreements. But it does seem a lot of money just to get into an open area of lakes and trees created by nature that shouldn't cost anything just to look at.”

"It costs a lot to maintain nature," Kristoph reminded her. "Besides, that's not too bad. Yellowstone in the USA charges €35 just to park a car before anyone even gets in. Free for TARDISes, of course. At least, I've never been asked to pay and display."

Marion giggled at Kristoph's remarks. They had visited most of the great American National Parks when they still lived on Earth and the TARDIS had invariably disguised itself as a log cabin or some other normal feature of the area. Today, indeed, it was disguised as a very wide oak tree in a forest clearing, identified by a pair of 'Greek' letters carved into the bark. Kristoph HAD paid for their visit even so - not only the entrance fee but a tour on a strange, articulated electric bus and other extras that meant they weren't walking around kilometres of wild parkland, much of it uphill.

"You really don’t have to worry about money," Kristoph reminded her. "Nor do you have to feel guilty about having it. I always tip waiters and chambermaids generously. And by stumping up these Euros we ARE helping to preserve a quite unique piece of planet Earth.”

Marion sat up on a bench beside the crystal clear Lake Kozjak – pronounced just like the 1970s TV detective - in the Plitvice national park of Croatia. She had a Wikipedia page open on her ultra-thin, ultra-light tablet and was reading about the landmarks they had seen already, as well as those promised by the tour. 'When it was all part of Yugoslavia the park was in the middle of the country, but since the breakup, it is on the border with Bosnia-Herzegovina. All that happened after I left Earth. I had to catch up on the new names of all those countries."

"They were the old names before Yugoslavia existed," Kristoph pointed out. "Which had a lot to do with the war, I think. But that is over now. The countries are at peace."

"I know," Marion said. "They even vote for each other at the Eurovision Song Contest, now."

"That wouldn't be a definition of international peace and reconciliation I've come across anywhere but Earth," Kristoph laughed. "What else do you know about the Plitvice Lakes from your Wikipedia entry?"

He laughed softly and just a little sardonically as if to imply that Wikipedia wasn't his information source of choice, but Marion ignored him. The database compiled by the Time Lords that was available through the TARDIS was not very helpful in this instance. The last Time Lord to visit Croatia did so when the country was ruled by the Venetian Doges.

“The lakes were formed by travertine deposits damming up the waters of several tributary rivers." she read, then thought about it critically. "It’s not completely unique. Pamukkale in Turkey AND the Mammoth Hot Springs at Yellowstone are both formed from Travertine deposits. And a place called Lagunas de Ruidera in Spain. But, still, sixteen lakes all connected by waterfalls and cascades is impressive. There's lots more to see. We're only at the lowest lake.”

“The Croatian government certainly thinks so,” Kristoph pointed out. He reached for Marion’s hand to bring her to a small jetty where a ferryboat with wooden seats and a fibreglass canopy let off one group of passengers and took on the next load. Aboard, there was tea, coffee and sandwiches as well as alcoholic drinks on sale as the quiet, environmentally friendly electric engine took the boat back out onto the lake.

“This is a bit like the Mersey Ferry,” Marion said. “Or… maybe Windermere. That’s a bit closer to this kind of scenery. Except Windermere is a glacial lake, formed quite differently.”

Kristoph smiled indulgently. Marion had once compared the great dunes of Astek Prime to a day out in Southport. It was how she got her head around the wonders of the universe.

But she wasn’t the only one talking about Windermere, as it happens. Marion looked around as she heard a middle-aged couple remark about how it was just like the Lake District but so very much bigger. Marion laughed softly and moved over to introduce herself to the couple.

“It is so very nice to hear English voices,” she said to Harold and Louise Holden of Leeds. “I hadn’t realised until now how long it was since I spoke in my own language."

“You live abroad, dear?” Louise asked.

“Yes,” Marion answered. “Mostly in France. We have a house in a little town called Parthanay, in Nouvelle-Aquitaine, and a villa on the Riviera.”

She didn't mean to sound boastful, just to tell the truth, which was that they owned two properties in France. It was a good cover story when she remembered how long she had been away. She had felt it keenly when she heard Mr and Mrs Holden talking to each other.

“Your husband must be doing well for himself,” Harold said, looking to where Kristoph had left the tea on the table and gone to purchase a glass of whiskey from the small bar. He had fallen into a casual conversation with another customer and only occasionally looked over at his wife and her new-found friends.

"Yes, he is," Marion admitted, though she decided not to mention what sort of job Kristoph did for now. Intergalactic Ambassador, former High President of a whole planet, were tricky subjects to bring into conversation. Even saying that Kristoph worked for the British foreign service might seem a bit too grand in these circumstances.

"No need to be embarrassed by that," Louise assured her, clearly sensing some of Marion's reticence. "Of course, it was plain to see at first glance. You are both wearing very well-cut clothes. Your husband looks like he was 'to the manor born'. But I think you were like me…. Married above your station. I was a shopgirl before I was married. In C&A. Harold took me away from all that. Managing director of the biggest shoe manufacturers in Leeds. Retired now, of course. We're enjoying our leisure, seeing some of the more unusual parts of Europe, not just the Costa’s and coach trips to Calais like most people.”

"This is certainly a very beautiful and unusual place," Marion remarked as Louise gave her a breath to get a word in. She had put her finger on things exactly, of course. But Marion wondered how her brand of unfettered chatter would do amongst diplomatic circles where it would be a social faux pas to notice that an ambassador's wife had come from much humbler stock.

"We looked at the waterfall below before coming up to the lake," Louise continued, thankfully moving away from the thorny subject of class mobility.

"Yes," Marion answered. "The size of it is amazing. I mean, nothing to something like Niagara Falls, but still amazing when you stand near."

'The way the water comes down over that huge limestone outcrop reminds me of the dropping well at Knaresborough," Louise added, leaving Marion non-plussed all over again. She felt a sudden tug of nostalgia as she, too, compared the mighty falls that watered Lake Kozjak with the Yorkshire landmark that had been one of the first places she and Kristoph had visited together – by car, before she even knew that the TARDIS existed or the man she was falling for was an alien.

"Sometimes," she admitted out loud and with a wistful tone. "Things were simpler when WE went to places like Knaresborough and Whitby for holidays." Her new friends couldn't possibly understand why she should feel that way. They very kindly didn't ask.

"Your husband is rather older than you are," Harold noted.

"You shouldn't say things like that," his wife admonished him, despite her own probing questions. "Don't mind Harold. He was never born to the diplomatic corps."

Marion smiled again at the thought of this plain-speaking couple in such circles and decided that the circles might actually be the better for it. Nothing either had said was untrue, after all.

"Yes," Marion admitted, remembering that Kristoph WAS more than a thousand years older than her. It really wasn't something that worried her. "I love him. He loves me. We're very happy together."

"Children?" Louise asked.

"Not yet," Marion answered, keeping her voice steady. Strangers had asked that question before and she had learnt to answer without undue stress. "Do you…."

That was a cue for Louise to pull out her mobile phone and access her photo album. Sons, daughters and grandchildren smiled at cameras one after another. Marion smiled and said the right things. Again, this was something she was used to.

At the bar, Kristoph carefully avoided looking like he knew the man with whom he had fallen into conversation. That was something he mastered long ago. So did the man. He wasn't going to ask if he learnt the technique at the same place.

"Those two people are perfectly fine," the Time Lord said. "Harold and Louise Holden, an honest if rather dull couple from west Yorkshire. I even checked for bio-dampeners and shimmer cloaks. They're absolutely human, absolutely safe. So is everyone else on this little pleasure boat. And given that one in a hundred people on this planet at this time in the early twenty-first century is descended from aliens who sought sanctuary on a non-First Contact world that's good going."

"So, there's no need to worry for another half hour, at least," Kristoph decided. "But since you're here, I suppose I might need to be on my guard?"

"You can leave it to me. I've been keeping an eye on you both since you arrived, anyway."

"You did it without me seeing you," Kristoph remarked. "You… are good at concealment."

"Free climbing comes in handy, too, in an environment like this."

"There's a lot of good free climbing to be had," Kristoph admitted. "I can't really take Marion around those spots, though. I'm strictly a tourist, just like Mr and Mrs Dullness of Leeds. You learnt the skills around Melchus Bluff, I suppose?"

"Yes, sir. You taught me."

"Good." Kristoph finished his drink and went back to join Marion and her new friends. When he looked around the young Time Lord had disappeared. His concealment technique was very good, indeed. He felt quite confident of an uneventful day. When the boat returned to the jetty the electric bus would take the same go up of thoroughly benign humans on a tour around the sixteen lakes, two major waterfalls and numerous cataracts of Plitvice. Marion was safe in such company and oblivious, still, to the danger from which he and his fellow Time Lord were shielding her.