[ Despite his words and the very real threat looming ever more as the seconds tick by, the Doctor does remain remarkably calm. There's more urgency in the tone of his voice and in the way that he moves, but he still absolutely believes they'll be fine.

If not potentially looking a little worse for wear. ]

Before I answer — ah, and do keep moving quickly. Faster than quickly, actually!

[ He glances over his shoulder again, and the thorn bush is rapidly coming closer. ]

Two points: one, you'll be safe, don't worry, it'll hit me first and I'm impenetrable. Well, nearly. [ Well, not really. But it sounds good! ] Two, just how fast can you move? There's a thorn bush and it's...quite large. Growing larger.