Four Letters of Love may have a star-studded cast but the scenery in Northern Ireland proved to be one of the film’s main characters, its director has said.

The movie was adapted for the big screen by Dublin-born author Niall Williams from his internationally-acclaimed 1997 debut novel of the same name.

Released last weekend, Pierce Brosnan, Gabriel Byrne and Helena Bonham Carter feature in the romantic drama set in the early 1970s.

“In Northern Ireland, the landscapes speak for themselves – they are a massive character in the film,” filmmaker Polly Steele told BBC News NI.

Four Letters of Love was filmed in locations including the Ulster Folk Museum in County Down, Murlough Bay in County Antrim and Dunfanaghy in County Donegal, in the Republic of Ireland.

Set in the west of Ireland, it is a story of love, faith and destiny centred around two troubled young people, Nicholas Coughlan and Isabel Gore, and their families.

For Williams, it is the first of his books to be turned into a film, and his first screenplay.

“I think the geography of it was important,” he said.

“I was very protective of that and happy that we could shoot it in Ireland and Northern Ireland.”

For Steele, it was the north coast of County Antrim which stood out.

“I think the one that is most dear to my heart is Murlough Bay,” she said.

“I remember coming down through this magical valley and arriving at this cottage right on the ocean edge and just going, ‘wow, this is it’.

“There was something classical about it. It felt like it held the magic.”

Williams was most impressed by a beach in Dunfanaghy.

“It’s an extraordinary, just empty, vast, beautiful place – magnificent on screen,” he said.

“And when Pierce (Brosnan) is painting in the dunes, I could watch that forever.

“A movie star, there’s something beyond just performance, some kind of mesmerism, which is tremendous.”

Brosnan stars as an William Coughlan who, following an epiphany, abandons his family and civil service job to become an artist.

Steele told BBC News NI that “Pierce was so supportive and extremely loyal to us”.

“I think he understood the artistic journey that his character was going on,” she said.

“He was a silent strength in this film coming together.”

Bonham Carter plays Margaret Gore, the wife of poet and schoolteacher Muiris, played by Gabriel Byrne.

As well as adopting the accent for the role, she also speaks Irish in one scene.

Williams said it brought back memories of Queen Elizabeth II’s historic state visit to Ireland in 2011.

“Helena speaks Irish at the end of the film, that sort of felt to me like when the Queen came to Dublin and spoke her two lines of Irish, it was extraordinary,” he said.

As well as the beauty of its scenery, the filmmakers had praise for those that worked on the production.

“The crew are extremely professional, lovely and kind and skilled at what they do,” said Steele.

“And Northern Ireland Screen were very supportive early on, backing us financially.”

But adapting a literary novel to the big screen was never going to be easy.

The production was seven years in the making.

“Filmmaking is a difficult pursuit,” added Steele.

“You must land many balls all in one go for a film to get off the ground – and sometimes it takes a long time.”

However the lengthy development process became strangely poetic for its writer.

“It would have been impossible to make this film quickly,” said Williams.

“The novel itself is about artistic struggle and our faith was tested many times.”