"Cybermen," he attempted to explain, "are a r--well, not so much a race as a deviation--of beings who gave up their humanity for an overdose of cybernetic upgrades. And a time scoop is generally a rubbish trick to use on a TARDIS lacking a recall circuit, but this certainly isn't Gallifrey, so I suppose that's right out."

The other question was less readily answered, but it was difficult to tell if his expression was sheepish or simply befuddled. "Well... we don't make a habit of it, I can say. More often than not, it just sort of happens."