Image caption Tom Hiddleston said he 'truly loved the character of Jonathan Pine - I was very moved by his courage'.

It's been a ratings smash, caused meltdown on social media and an online leak of the last episode has made global headlines. But is the success of the TV adaptation of John Le Carre's The Night Manager down to its star names - or the enduring appeal of the spy?

The mini series, a BBC co-production with US TV channel AMC and the Ink Factory - the latter company started by two of John Le Carre's sons - stars British actor Tom Hiddleston as the enigmatic Jonathan Pine, who goes undercover to try to expose the activities of billionaire arms dealer Richard Roper, played by Hugh Laurie.

The story also features Olivia Colman as security services figurehead Angela Burr - who was a male character in Le Carre's 1993 novel.

Each episode cost an estimated £3m to make, and one executive producer, the Ink Factory's Simon Cornwell, says the lavish adaptation was "a risk."

"It's a difficult book to adapt," he says, "and there have been quite a few attempts to make it into a film, it just didn't work. It needed six hours to explain the story.

"But to all intents and purposes, it's been written and shot as a film - we just hired one director, Susanne Bier, for all six episodes. I always think of it as a film - just a six-hour one."

Image caption Hiddleston has gained new fans from his performance in The Night Manager

Bond audition

Despite widespread critical praise for the story, much of the attention from social media has focused on Tom Hiddleston, speculating that its success can be attributed to his popularity with viewers - particularly when he appears without his shirt.

The actor, already well-known for playing the Norse god Loki in the Marvel comic adaptations, is also currently starring in the Ben Wheatley film High Rise.

A recent sex scene in The Night Manager made Hiddleston's rear a number one trending topic on social media - while other Twitter users have described his part as his "audition for James Bond" - a reference to the sharp suits, glamorous locations and espionage that punctuate the series.

Cornwell believes that "we hired a superstar in the making. I don't think British audiences have ever had so much screen time with Tom Hiddleston before.

"Viewers have been able to tune in week after week to see him and have become invested in his character, and with him.

"What's great for me is when I go and get lunch in cafes and I overhear people talking about him in the latest episode - that's when it hits you how popular the show is."

Image caption Tom Hollander is also in the series as Corkoran, who works for Hugh Laurie's character

'Integrity and moral courage'

While the actor has previously stated he'd be interested "if Bond ever came knocking", Hiddleston says "story is key" as far as The Night Manager is concerned in his decision to take the part - and he thinks its appeal is "down to a good spy story never going out of fashion".

"I wonder why that is?" he speculates. "I've always been fascinated by that decision to sacrifice yourself, which is essentially what a spy does.

"There is an erosion of yourself, you have different passports, no attachments, no dependents, no address. You are in the service of something higher and I think that's why most of us are so interested.

"I truly loved the character of Jonathan Pine. I was very moved by his courage. Isn't there a saying that 'evil persists when good men do nothing'?

"Pine is impelled to stand up for something and risk himself for a greater good, and that takes huge integrity and moral courage."

Image caption Hugh Laurie plays a billionaire arms dealer

'Essential reboot'

However Hiddleston also wonders if the story would not have been relevant without an "essential reboot".

Writer David Farr and director Bier updated many aspects of the original 1993 post-Cold war novel to include Colman as a female security service agent, but also to set it around the Arab Spring in 2011, with locations in Iraq and Afghanistan.

"It now has a pertinence and a relevance to today," Hiddleston claims. "I think we can see all too clearly that we live in a dangerous world, and we know that weapons are often sold under the table, and we know that sometimes governments can be involved.

"We don't know where those weapons end up, and we don't know where the enemy is. Isis and Al Qaeda have made the threat to our freedom so intangible, but I feel this story weaves it into a clear narrative and it's something we can believe.

"But we also needed Olivia Colman as Angela Burr - she is very much the heart of the show. I was told that most of the security services these days happen to be female led, we just don't always know their names - but she's a different class, a different sex, and it adds a new dimension to the story."

Image caption Olivia Colman is described as 'the heart of the show'

Danish director Bier, who won an Oscar in 2010 for her film, In A Better World, says before the series aired, "the one danger I was worried about was that audiences would switch off half way through".

But unlike another costly adaptation, War and Peace, audience ratings for the show have actually increased as the series has gone on, rising from six million to a peak of more than eight million viewers tuning in for last Sunday's episode on BBC One, when a major character was killed off.

Leaked episode

However, an online leak of the last episode after DVD and Blu-Ray editions of the series were sent out early, could dent ratings for the series finale this weekend - as well as leaking plot spoilers over the internet, before the series starts in Australia and the United States.

Cornwell says he has no comment on the issue, but believes the show had, overall, "been event television".

"It's the fruit of a golden age of TV where big names are lining up to take part because the stories and the budgets are so good - plus actors and directors can invest in something unfolding before audiences, week after week."

In an unprecedented move for a John Le Carre adaptation, which has also included the films Tinker Tailor Solider Spy, The Spy Who Came In from the Cold and 2005's The Constant Gardener, there's even been speculation that there will be a sequel for The Night Manager. That though, says Cornwell, "is most emphatically a rumour at this point".

The final episode of The Night Manager will be shown on BBC One at 21:00 GMT on 27 March.