James Marsh had doubts about making 'The Theory of Everything'.

The biopic of Professor Stephen Hawking, starring Eddie Redmayne and Felicity Jones, has received widespread acclaim since its release, but the 51-year-old director has confessed he wasn't certain the film would be a hit.

Speaking at the British Academy Film Awards (BAFTAs) at London's Royal Opera House last night (08.02.15), Marsh was asked whether he had any doubts while making the film, to which he replied: ''Every day.''

What's more, he stressed the need to ensure ''all the details'' of the film are accurate in order for it to be a hit.

He explained: ''You're doing something which if you don't get right all the details, the whole thing is going to fall apart. That's as much down to the cast as to what we do.

''So, you're kind of in this situation every day where you keep your standards very, very high and if you don't, then the film is just going to disintegrate around you.''

Redmayne - who plays the role of Professor Hawking - won the Leading Actor BAFTA award for his portrayal of the theoretical physicist, after winning the Golden Globe Award for Best Actor - Motion Picture Drama in January.