Cillian Murphy has been extolling the virtues of Peaky Blinders – the BBC 2 series in which he has a starring role.

"It is some of the best writing I have come across, and I never expected to revisit a character like that over and over,” Cillian said, in an in depth interview in today’s Observer magazine, of which he is the cover star.

"It will be about 30 hours of television when we have finished and to shine a light into all these weird parts of the character’s psyche that you would never ever get in the compressed version of a feature film or even a play, that is an extraordinary gift."

Production on Season 4 of what has been a hugely popular series has begun, and a fifth series has also been commissioned.

“I am very lucky that it came along," he said of the series – in which he also has a role as co-producer, "I have always just been about the work."

Murphy also talks about his latest film, the Ben Wheatley-directed Free Fire, which opens on March 31. In it, Murphy and his co-star Michael Smiley play two Irishmen trying to by guns in Massachusetts in the 1970s, presumably for the IRA – though this is never explicitly stated – when a vicious shoot-out occurs.

"That was the context – that's why Irish fellows were out in America buying guns," he reflected, "but it is not a political film in any way."

The film also stars the Academy Award-winning Brie Larson (who took her Oscar for her performance in Lanny Abrahamson’s The Room) and rising Irish star Jack Reynor (best known for his starring role in Abrahamson’s What Richard Did).

"The film is unique," Cillian added. "Ben spoke about it to me at our very first meeting all those years ago and I was very taken with the idea of making a film that is one long gun-fight."

Murphy also speaks about his decision to repatriate to Dublin from London, stating that it feels natural.

Murphy’s next picture is the World War II drama, Dunkirk, which sees him working once again with director Christopher Nolan, for whom he starred in Batman Begins. "Everybody knows what happened at Dunkirk, so it can't deviate too much from the facts. It is not like Inception or Interstellar, there's no major reveal."