UPDATED, Monday, 7:36 AM: The financier for Jim Sheridan’s H Block told Deadline this AM that “the production was postponed due to timing issues with regards to the short time element with Pierce Brosnan’s availability that left us with a very small window to get him wrapped on his production date. That along with creative elements that needed to be addressed with Cillian [Murphy] caused us a conflict with his schedule and we are planning to remount the production in March. There was no financial issues surrounding this production,” said Brad Feinstein, CEO of Romulus Entertainment. A March production restart would mean that Murphy is out because of a scheduling conflict.

PREVIOUSLY, Sunday, 12:06 PM: Production is being postponed on Jim Sheridan’s next film H Block. That has caused an issue for Dunkirk‘s Cillian Murphy who had a short window of time to shoot the film (as a key lead) before he started the series Peaky Blinders for the BBC in March, we’re told. However, we hear that the producers are re-grouping and so the entire project is now stalled. Sheridan, of course, is one of the best indie filmmakers around and considered an actor’s director.

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It’s not clear how long the production postponement (first reported by The Sunday Times) might take so that will likely be a determining factor for all actors who committed to doing this.

Sheridan, the three-time Oscar-nominated writer-director behind such superb films as In the Name of the Father, My Left Foot, The Field, In America and The Boxer had cast Murphy and Fifty Shades star Jamie Dornan to lead the cast, with Pierce Brosnan in a key role in the film. The script originally was written by Tony Devilin and Gavin McCloskey, and Sheridan and Nic Sheff finished a shooting script. The actors will all now have to look at their schedules.

H Block is the true story of the Maze Prison escape, known as the Great Escape when the story unfolded in Northern Ireland. It was at the maximum-security prison that became a source of propaganda used by the IRA. Thirty-eight prisoners escaped from H-Block with only 19 recaptured.

In the escape, one officer died of a heart attack after being stabbed (one of four injured that way). In all, 20 were injured, including being stabbed or shot; one prison officer was shot in the head but survived. The escape was a violent breakout that included hostage taking and ended up being the biggest in both British and Irish history.

The film is being produced by Dylan Sellars. Dan Halsted is the exec producer.

Mister Smith Entertainment handled sales in Cannes for the film, and Brad Feinstein’s Romulus Entertainment said they were fully financing the film with his partner Joseph Ingrassia. WME and UTA have been repping the film rights in North America.

There is also a competing project about the same subject matter but with lesser-known filmmakers and cast. That one, called The Maze, was written and directed by Stephen Burke and produced by Brendan Byrne and stars Tom Vaughan-Lawlor and Barry Ward.

Nancy Tartaglione contributed to this article.