Benedict Cumberbatch: "I have been the bearer of a few secrets this year"

Benedict Cumberbatch first set hearts aflutter in the BBCs hugely popular Sherlock, which returns on New Year’s Day, and has since made great waves playing Julian Assange, Khan and now, as the voice of Smaug, the dragon in The Hobbit. He has also made a big impact on the world of otters. He talks to Donald Clarke