The actor commented:
It was a glued-on beard. I wouldn't be able to grow a full-on beard like that in time. They had to remove it with a substance smelling like white turps.
It's also been confirmed that Smith has filmed special scenes, scripted by show runner Steven Moffat for the new interactive exhibition opening at London's Olympia next month, the Doctor Who Experience.
It gives a sense of the TV show. I've filmed some scenes for the experience. It places you, the fan, at the heart of the action and become the companion, in a sense. There's a Tardis, which you can go on. The museum has all things Doctor Who. It should feature costumes from all the Doctors over the ages, and I'm sure I've got a few bits in there.