Sherlock star Benedict Cumberbatch has admitted that he sometimes worries about some of the more obsessive fans he has gained since starring in the BBC One hit.

The actor, who will soon begin work on the third series of the show, has accumulated a devoted following of female fans – known as Cumberbitches – since playing the detective – but admits he is still wary of his new-found fame.

“There is some obsessive behaviour, which is quite worrying. I worry for them, not for me,” he said.

“I’m still very sensitive and wary of people recognising me. The only thing that really annoys me is people trying to surreptitiously take a photo on their phone without asking.

“I feel it’s cowardly and a bit pathetic. Just ask me if you really want me to have a photograph with you.”

While Benedict’s fans are waiting for the new series of Sherlock they will have the chance to see their idol in the new period drama Parade’s End, which begins on BBC Two on August 24.

However they may be surprised to see the 36-year-old looking very different, as he donned a fat suit for his role as English aristocrat Christopher Tietjens.

“I kept saying, ‘He’s a fat, blonde Yorkshireman. Why do you want me to play this part?'” Benedict revealed.

“I insisted on the fat suit and plumpers, these things you put in your mouth, but I would have liked to have gone a lot further. I wasn’t fat enough!”