I took Benedict Cumberbatch [his co-star in Starter for Ten and Atonement] up the Brecon Beacons a few weeks back. It was fucking hilarious. We started late because Benedict’s eyes are bigger than his belly, and we’d stopped in Hay-on-Wye and he saw some steak-and-kidney pie, and he had to have it: “Oh, we’ve got to stay and have some pie.” We finally started walking up this mountain, Pen-Y-Fan, at half past three. And of course the cloud came down. But I thought: I am not stopping, Ben, I am not stopping because of your bloody pie. So we kept walking and ended up with 5ft visibility. It was brilliant, though, amazing; this sheer drop, 1,000ft down, just to your left. You knew it was there but you just had to trust you wouldn’t step out into it. And then the cloud cleared for 10 minutes … I just felt I was in heaven.