'We can’t say the things we really want to say about people in real life,’ Cumberbatch adds. 'So it’s fun to vicariously enjoy someone else being rude and Sherlock carving his way through life creating all the havoc that John very often has to patch up behind him. It always goes back to their relationship, and that is very much what the first new episode is all about. There is a mystery in there, but it’s more about whether they are going to get back together. Because it’s not an easy thing [for Watson] to overcome – two years of grieving.’