It's all AU.

Following Rose's advice, Lucy pinned up a note on the board in the lobby:

Harry,

I'm dreadfully sorry I ran off like that and I'd really like to talk to you. Please come and find me as soon as you see this. My room number is the same as the number of the room we had in that lovely hotel in Edinburgh last year - you remember?

If I'm not there, leave me a note to tell me where you can be found.

Please, Harry. This is important.

Lucy

Then she went back to the room she'd occupied on her previous visit – all her things were still in there, which saved a lot of trouble. She waited up for another hour or two, but there was no sign of Harry. In the end, she gave up and went to bed, and slept soundly, exhausted by the long night.

Morning. The morning after the night before, and the Doctor was banging frantically on the door of the other TARDIS.

Really, really frantically. Because he'd spent the night lying beside Jack, wanting to make sure he was all right, and when Jack woke - headache mercifully subsided and his shields much more intact - they'd talked, their quarrel of the evening before forgotten, and the Doctor had told Jack he was furious with the Master for messing with his lover, and Jack had asked him to show him just how furious, and, well, the Doctor had had to go to some lengths to convince him...

And then things had suddenly got really out of hand.

"Come on!" he shouted, almost sobbing, battering at the TARDIS door with his fists. "Please! Come on!"

Harry woke in the same hotel room he'd gone to sleep in.

He was surprisingly un-worried by this. He was annoyed at missing the celebrations last night, and itching to get going on the business of ruling Great Britain, but this was the most exciting thing ever to have happened to him and he was eager to explore.

He got up, washed with products amazingly similar to his own at home, dressed in a suit he was positive had come straight from his own wardrobe, and wandered out into the hall, impatient to see what was outside. He walked straight past the note Lucy had left in the lobby without even noticing it and wandered out into the sunlight.