Benedict Cumberbatch found it difficult to voice The Grinch because he had to work by himself.

The 42-year-old actor brings to life the Christmas hating titular character in the upcoming Illumination Entertainment animated film - based on the 1957 Dr. Seuss book 'How the Grinch Stole Christmas!' - and he has admitted that he ''got stuck on a couple of things'' as being alone in the recording booth is a ''very peculiar process'' for him.

Speaking about the part on UK TV show 'Lorraine', he said: ''I was literally in a wee booth by myself. No other cast members. It's a very peculiar process. Which can be a little bit insane. You can get stuck on a couple of phrasing... [you think], 'Surely you've got this by now!' ''

Although it is a festive film, the 'Sherlock' star is certain his own children - Christopher, three, and one-year-old Hal, who he has with wife Sophie Hunter - will watch the film repeatedly not matter what time of year it is.

Referring to his kids watching it over and over again, he said: ''It only dawned on me yesterday when people said, 'You do realise it's a Christmas movie'. [I thought] 'Oh yeah, this will have a life beyond this Christmas.' ''

The 'Doctor Strange' actor also opened up about the new moustache he is sporting for an upcoming role in an upcoming thriller called 'Ironbark' - in which he portrays a spy called Greville Wynne - and the star admitted that he doesn't often get to ''choose his own style of facial hair'' as it is determined by the roles he takes on.

He said: ''I very rarely get to choose my own style of facial hair, or hair, for that matter. It's all paid for kind of. It's all kind of designed for a look for a part.

''This is a man called Greville Wynne. It's more than just a moustache. [It's an] extraordinary true story about a man who became one of our main key sources of information during the Cuban Missile Crisis.''