Haha, thanks.
The interview's not for another hour yet, but thanks all the same.
Thanks for the suggestion both of you. I don't think it is these though, because it wasn't flickering very obviously and it was a night-time star blue in colour (why I thought it was a weather balloon, since they're silvery). It was also moving much faster than a flying lantern, it cleared my bedroom window's field of vision in under 20 seconds (went over the house so I lost track of it).
I also thought it could have been a satellite - that was the first thing I thought of, but it still seemed like it was moving too fast and, as you said, I couldn't figure out why it would weave about.
I've actually seen this same thing before, once when I was in Cyprus when I was about 13-years-old.
So, is a weather balloon not a possibility?