TV viewers in Britain complained they couldn't understand the "mumbling" in SS-GB, a new series about what life in England would be like if the Nazis won the Battle of Britain.

The series, based on Len Deighton’s novel set in a Nazi-controlled 1941 London, also came under fire for errors in an opening sequence, which featured a Spitfire Mk IX, which was not introduced until 1943.

But most TV viewers took to Twitter to complain about the sound quality, insisting Riley's dialogue was mostly undecipherable.

One wrote: "Dear @BBCOne Please sort the sound out on SS-GB. You cannot hear what the cast are saying. Muffled and low pitched. #ssgb", while another added: "SS-GB is a mess. Wooden acting and mumbled dialogue so far. Uninteresting characters. Such a wasted opportunity."

A spokesman for the BBC tells The Sun, "We will look at the sound levels", while a representative for Sid Gentle Films, the production company behind the project, said, "We were unable to source a spitfire from 1941 which was suitable for production purposes."

The show was created by writers Neal Purvis and Robert Wade, who penned the screenplays for Bond movies Spectre, Skyfall, and Casino Royale.