Colin Firth is tackling one of his toughest roles to date as Jim Swire, the man who helped fight for justice after the devastating tragedy of Pan-Am 103.

Losing his daughter, Flora, to the airplane’s explosion, Swire became a central force in an international fight to find those responsible, facing world leaders who became roadblocks as more information came to light.

Over the course of five episodes, Colin leads the cast as Swire in a condensed interpretation of what happened, as the case continues 36 years on from the initial incident.

Speaking ahead of the series launch, Colin talks about the importance of retelling this story, his knowledge of the case, and how overwhelmed he felt about recreating this fight.

Find out what the real Jim Swire thinks about Lockerbie: A Search For Truth here.

I think anyone of my age, certainly based in either the United Kingdom or the United States, will remember this in a way that’s really quite impactful.

It’s obviously a very long time ago, and I think time plays strange tricks on you, because there’s a part of me that couldn’t believe that it was more than 30 years ago. Then in another way, it feels like so much has happened since, particularly as 9/11 happened in the intervening years.

And so, to find oneself brought back to that moment of hearing about it had a real impact. It was trying to trace back to what one thought and felt at the time, and what one has felt subsequently; how much that’s remained in one’s mind, given all that’s happened since. And that’s speaking as a bystander, of course, and realising that this has been a profound part of many, many people’s lives ever since.

I didn’t know very much about Jim Swire beforehand. I do remember the story of one of the relatives trying to challenge the security system at the airport and then obviously reading the script led me to look him up.

I was just overwhelmed by the relentless sadness of his journey. The twists and turns of it; and revisiting what I thought I knew about the trial, about the investigation and all of the subsequent events.

I thought it was the most remarkable story, a painful one, but also in many ways an impressive one. I thought that if you go through the steps that that man has been through, it was very much a story worth telling.

I just want to be clear that whenever I talk about Jim, I'm going to have to at least partly talk about my Jim and David Harrower's [the show’s writer] Jim, which we hope resonates with the real Jim. I think one of the things that's so extraordinary and so particular about the character of Jim Swire is the journey and its duration.

The point where he finds himself today couldn't be further from his starting point. This is a man who, according to my understanding, had a basic trust in institutions and the institutions in which we live. He wasn't a natural activist, as far as I can see. He isn't someone who inherently distrusted establishment. I think he made the assumption that governments seek to tell us the truth, as do law enforcement and the legal profession. That was his starting point.

Obviously, we find Jim in a state of very raw emotion and profound grief. His motivation was to find out the truth and also to gain understanding. They're not exactly the same thing, I think. If you want to find out the truth you want to make sense of something which is inherently unfathomable.

So, I think he set out in good faith looking for answers, which he fully expected to be forthcoming as far as possible. Doubts crept in once he realised that they weren't as forthcoming as he expected them to be.

I think I was quite overcome by the degree to which Catherine inhabited the part. Almost a shock, actually, to feel something that real opposite you and so uninterested in melodrama. It felt mature and I found it quite chastening. It makes you feel you shouldn't act, just play off what I'm seeing because she exudes strength and intelligence. That really focused those scenes for me.

I didn't feel like I had to go searching for all those incomprehensible things about this experience because there are always going to be incomprehensible things. But to have her as that anchor and emotional reality just made my work technically easier. It was emotionally sometimes quite disturbing, but she took her job so seriously and it was done with such respect as well.

She clearly had enormous respect for Jane Swire and her family and that came across when we were shooting those scenes.

It’s very hard to take the measure of how much an environment informs your performance. It almost certainly does, but I don’t think one is necessarily conscious of how that happens. You feel a difference in temperature, you feel a difference in atmosphere and it also affects just something as straightforward as what you’re wearing.

I think it definitely brought home to me the scope of the journey — the scope of it is enormous in terms of time, in terms of experience, in terms of the search for answers and the information that comes in, some of which turns out to be trustworthy, some of which turns out not to be.

It brought home as well the geographical contrast because it couldn’t be more extreme really: it took a desert in North Africa and then the south of Scotland to realise how far this man had travelled in literal terms into the unknown, out of the familiar and out of his comfort zone, through the streets of Tripoli with all its perils on a mission which is perilous anyway.

This is a man who went on a journey having no idea really how safe he was or what to expect. As he himself has said, he fully expected that he’d either be taken prisoner or even shot. You know, Gaddafi was one of the most notoriously unpredictable, powerful people on the planet. Jim was going into the belly of the beast with this unofficial mission with no support, no back up.

It’s always very hard to single a scene out and say, ‘This was particularly striking.’ There were ones which I think I needn’t spell out, which one always avoids. It’s always a huge challenge because you know, who the hell are you to really try to represent a moment that is beyond your comprehension? But in this profession it is what we’re supposed to do and so you do what you can to draw on your own understanding and sense of empathy and your sensitivities to try to inhabit something which is very extreme in terms of technical challenges.

The thing I think was most striking to me was having to represent legalese and scientific data. There were a lot of monologues about that stuff because as time went on, this is what he [Jim Swire] was faced with. There were the politics, all of which has its own language somehow, then there was a legal case being brought forward, which certainly had its own language, and then the whole business of evidence — I had to do a crash course in a lot of this and it was a pretty deep dive over the course of a few weeks. As indeed did he, of course, over decades.

This is a man trying to gain understanding and the information comes in ways that have to be processed in order to give him a clear comprehension. Otherwise, it’s like algebra. On top of that, just the sheer technical understanding is one thing, but if also you’re sceptical of the reliability of it, if you’re sceptical of whether you’re being told the truth, it creates an ever-increasing, tortuous tangle.

Having to try to track that in long periods of dialogue or monologue, I found that extremely challenging. Any actor will tell you that doing technical stuff is some of the hardest stuff to even learn, let alone inhabit like a human being. You can learn those lines, parrot-fashion, if we’re talking about electronic circuit boards, or fragments of a case, or the nuances of legal procedure… but to actually deliver it as if you actually have a mind and a soul is a whole other challenge. Because this content wasn’t just for the purposes of information or exposition: it had to express what this man’s experience was.

You have to be trying to understand a person’s experience and be trying to represent that so that other people can share it in some way. I would say that that was one of the most difficult aspects.