You've said previously that the decision to play Jimmy Savile was not one you took lightly. What made you say yes?

First of all the caliber of people involved - Neil McKay, Jeff Pope, Sandra Goldbacher, and so many stalwart actors of great repute. Incredibly respected, premier league people. I've worked with Jeff before quite closely on a number of projects such as Philomena and Stan and Ollie, and when I looked at the scripts and discussed with him and Neil and found out about the survivors' involvement it was clear this was being done properly. I've played a few real people in my time, some good and some not, although Savile is certainly the worst.

The big question is why are you doing it? That's the question you have to answer, and that's the question the script has to answer. If it does then you're on the right track, and here it was clear from the script and my conversations with Neil and Jeff that this was being done in an ethical, responsible way. On balance, I think it is better to make this drama than not to make it. Drama can capture things in a more nuanced, detailed way that is more illuminating than a straight forward documentary, of which there have been many. We've seen the power that a well-made, factual drama can have. I knew this wasn't without risk. Nothing that's interesting to watch is ever without some kind of risk and this had more risks than anything else I've done, but knowing that I had the best people with me I thought it was worth it. I feel this series is a really strong piece of work and that all the people involved in it - survivors, cast and crew - should be proud with the job that's been done.

The involvement of survivors was part of that original conversation I had about becoming involved myself. Neil had already spoken to many of them and we knew some were going to be included on screen to give their accounts and to literally give them a voice. Although even without them on screen I think the series does that, because the depictions of what happens are based on their testimony. It's crucial that when making a drama like this you walk side-by-side with the people whose experiences you are depicting. That's the grown-up and responsible way to do this. Having the participation and endorsement of so many was absolutely crucial to the process, and everyone has made sure this was handled sensitively. That's why it's taken a long time for the series to get to screen - you can't just chuck it out there, you've got to do it properly, and be fastidious and diligent. To not do that would be a dereliction of our duty.

How do you approach playing someone like Jimmy Savile in terms of research and preparation?

I've played a number of real people and in some ways I didn't treat him any differently. I feel an overwhelming sense of revulsion about Jimmy Savile and the way he operated, but I put my personal revulsion to one side to play him convincingly because the risk with not doing that is him coming across as a sort of pantomime villain, which would lack credibility and therefore not do this justice. It had to be grounded and believable. In terms of performance, I like to take physical things - the way someone dresses, the way they talk, and the way they move - and assimilate all that to try and find who they are and use that as a way to get inside their skin. But I'm not a method actor - I can switch it on and off like a switch so I certainly didn't each my lunch as him on set. When we stopped filming I immediately snapped out of it.

And that was particularly important here because on a number of occasions I was working with younger cast members - often women in their late teens or early twenties - playing the role of people even younger, the people Savile preyed on. It was really important that everyone felt at ease and comfortable. Even though scenes of the abuse are implied rather than shown we worked with an Intimacy Co-ordinator, Jenefer Odell. Jenefer was really helpful and made me feel at ease because not only can there be anxiety for the women who are playing these roles, it's not very nice for me either. It's hard to be light-hearted on set when you're making something so serious, but I always made a point of meeting the actors who were playing Savile's victims before I started the costume and make-up process to transform into him. Just to say essentially "Hello I'm Steve", and have a normal conversation with them, and make it clear that we're actors doing a job, albeit one with huge responsibility. To represent scenes of assault and the abuse of power in these situations is a potentially traumatic thing to do, so you have to be careful and you have to have everyone feel relaxed enough for it to be credible. Then once you've been transformed and you're acting you feel like you're in a safe space with someone, they don't feel like they can't be vulnerable, and you can all do justice to what we're depicting.

Were there any pitfalls you were keen to avoid with your performance?

I didn't want to be just doing an impersonation. That's the main thing. An inherent problem of impersonating someone accurately is that it can strangely make people laugh - and of course you don't want to do that here, because it would trivialise this. There's always that danger if you're trying to be accurate. To avoid that, I committed to playing the person underneath. The front Savile adopted was incredibly theatrical – he often put on ‘an antic disposition’ - which lends itself unhelpfully to comedy. I had to be really mindful of that and think about it in different ways to inhabit it credibly and not undermine the fact of what a terrible person he was.

You met with some of the survivors who contributed to the series during production. What was that like?

Firstly they were good company and interesting people to talk to, but even more it made me realise the huge responsibility we had and why it was important to get this right and do their stories justice. There was an added weight to filming when I'd previously spoken with the real people, when I'd then be doing a scene with actors portraying the same people 30-40 years ago. And of course it was quite a remarkable, surreal situation for them - to essentially see their attacker recreated - and we were aware it could have been potentially triggering for those who chose to come to set, so everything was done in a supportive and responsible way. Fortunately I think it helped once they saw we were filming the series with such care and diligence.

What do you hope viewers will take away or learn from watching the series?

The point that I hope people will take away is that they learn to listen to victims and survivors, and learn to take these things seriously. If you treat people with respect and we act together then you can avoid something like this from happening in the future. As the series shows, the people who did have information about Savile and those he preyed on were so often people with ostensibly low status who couldn't change things. The people who could have made things better were people in positions of power, and they are more culpable than the people who did not wield that power. Let's make sure we learn from this and therefore avoid it happening in the future. I think most institutions now have protocols in place for reporting such things, and we're much more cognisant of safeguarding in a way society was not 40 years ago, but we can still learn so much from looking back. This series is a study of how someone can manipulate people and whole groups of people, and it's worth watching to learn from that. And I hope people learn about being vigilant to signs of abuse and manipulation, and the people who perpetrate these crimes.

I do also hope that viewers don't find the series too bleak, and will also take away from it the fact that there are good people too. There are people who tried to do the right thing, and people - not least the survivors involved - who showed and still show great courage. There are lots of decent people in this world who want to do the right thing. It's about being vigilant but not disillusioned with humanity.