‘It’s a false sense of entitlement that we have to get rid of, because it can have catastrophic results. This is a story that recommends modesty. I think arrogance was the main problem and it’s big a problem today in the way things have been handled recently in this country.”

Screenwriter Christopher Hampton, who has adapted The Singapore Grip for the small screen, clearly sees recent parallels to the tale told in JG Farrell’s last novel.

His epic treatment of Farrell’s 700-plus pages comes to ITV this month and tells the story of what Winston Churchill called “the largest capitulation” in British history – the fall of Singapore in 1942. The book was the third in Farrell’s “Empire” trilogy, his exploration of the consequences of colonialism.

Japan’s victory at Singapore was overshadowed globally by the events of Pearl Harbor just two months previously, but it was, nevertheless, calamitous for the British Empire: it led to the capture of nearly 80,000 Allied soldiers, the death of thousands more, and an evacuation on a massive scale.

Hampton’s own uncle was among the desperate throng who boarded ships and fled the island just before the invasion. The screenwriter (an Oscar winner for Dangerous Liaisons) therefore felt a personal connection to the story.

He had also known and admired JG Farrell when they both lived in London’s Notting Hill during the 1970s. Tragically, Farrell drowned off the coast of Ireland in 1979.

Hampton was determined to keep the comic, often bemused, tone of the author’s prose in his screenplay, highlighting the military incompetence, casually racist society and all-round complacency that led to Britain’s downfall in the region.

“He treats a serious subject with wit and lightness, which gradually darkens as the story darkens,” explains Hampton. “I wanted to preserve the comedy where I could, and it’s very amusing in places. I also wanted to keep the balance between the real-life military characters and the family saga, giving them context.”

Hampton, who also served as an executive producer on the project, sounds almost embarrassed when he adds: “I found the whole process of adapting the book immensely enjoyable. Nobody should be paid for having so much fun.”

He was blessed with a cast able to swing with these nuances of light and shade. David Morrissey plays Walter Blackett, a complacent rubber-­company executive focused only on what works best for him. Charles Dance is his more principled colleague, Old Mr Webb, and Luke Treadaway his equally well-intentioned but wet-­behind-the-ears son, Matthew.

Jane Horrocks and Georgia Blizzard play Blackett’s wife and daughter, while Coronation Street alumna Elizabeth Tan is the mysterious and disruptive Vera Chiang.

Treadaway clearly delighted in his role: Matthew Webb is a late arrival to the party, and it is he who takes the audience on his journey into the rich, complex world of Singapore, beginning six months before the invasion.

He soon becomes the subject of two rival women’s affections, but it is in his protestations against Walter Blackett’s machinations for his rubber company that Matthew emerges as the most generous-minded of the characters. Treadaway describes him as “progressive for his time” in his attitude to native workers’ rights and not wanting to strip the country of its assets without putting something back.

The actor says he saw his character as one who learnt as he went along. “He wasn’t putting his body on the line, he was just less shackled to the status quo.

“My ethics and values come down firmly where Matthew’s values are. In the scene where I’m asking Walter about how he treats his workers, I found myself getting angry with him, and everyone like him.”

While it is all too easy to see the complacence and arrogance of Farrell’s characters in many of our contemporary public figures, Treadaway is stumped when I ask for a real-life modern equivalent of the more earnest, honourable Matthew Webb.

Hampton believes the challenge lies in the character’s innocence. He explains: “I don’t think this is a very innocent age. I feel that part of the story is that of an innocent who, in the course of the story, gradually gets educated. I think that there are genuine idealists in the world, though, and he’s in that family.”

The challenge of creating an epic feel for “a Second World War film shot in the tropics of Southeast Asia” has made this the biggest professional project yet for producer Farah Abushwesha, who previously worked with the same company, Mammoth Screen, on The ABC Murders.

The series was shot entirely in Southeast Asia, with Kuala Lumpur doubling for wartime Singapore. The neighbouring houses owned by Walter Blackett and Mr Webb on screen are, in reality, a stone’s throw from one another in the highest part of the city, which remains surprisingly lush and green.

The producer was delighted with the different moods the design team were able to create, each interior reflecting its very different inhabitant. “We can all identify with the beautiful, cool house the Blacketts have created,” she laughs. “It’s fashionable, cool, absolutely pristine, the perfect house for a modern European living in Asia.”

Mr Webb’s house is darker, pokier but more characterful. “He’s immersed himself in the country’s culture. He’s collected things that are quite unique. It’s a true reflection of his personality.”

Other locations that jump out on screen include: the “Blue House”, where a bizarre dinner party takes place in the second episode; “an old clan house that dates back centuries, with little bits of water, dark wood, so much history”; and the recreation of the Battle of Slim River, filmed in southern Malaysia – “lots of Japanese extras cycling over rocky ground on bicycles from the 1940s – it looked magical”.

Abushwesha still can’t decide which was more temperamental – one of their leading men, who happened to be a monkey with very strong facial expressions, or the weather. Certainly, the latter failed to behave on one of the most important and, no doubt, expensive, shooting days of the entire project.

“It was a circus day. We had hundreds of extras, special effects, groups of singers, a cannon to shoot someone from. We’d flown people in from Thailand. We had 10 hours to shoot, and it rained for seven and a half of them.

“There was a foot of water on the ground. What could we do? We couldn’t drink, so we went to a café across the road, ate loads of cake and waited. Finally, we got the shots, but it was maddening.”

Treadaway says acting in these huge street scenes was thrilling, “the nearest I’ll have to time travel”. He hopes the series will spark conversations about the past: “We look at it and say, what’s changed? It’s a fascinating prism to look into another world, and have our own world reflected back at us.”

Is there hope, too, amid all the hubris and eventual devastation? Hampton believes so: “It resides in the understanding that arises between the races and the open-mindedness that leads to that. That’s the big positive of the story, and in the young people who are open to what’s happening. They’re aware of the world in a way that the older generation have become too boiled in aspic to notice.”

The Singapore Grip will air on ITV on Sunday 13 September at 9pm.