Obviously, this article contains spoilers for Season Six of Game of Thrones.

I meet Roger Ashton-Griffiths on his way up the stairs at Bafta HQ in London. Dressed in a pair of thick tweed trousers, a blue fleece and crocs, he’s cheerful and keen to show me around. Known for his role as Mace Tyrell, the bumbling father of queen Margaery (Natalie Dormer) in Game of Thrones, Ashton-Griffiths is perhaps an unlikely part of one of the most intense fandoms of recent years: though he knows the name of every single waiter and barman at Bafta, he struggles to recall names of Thrones characters. “I knew nothing,” he says happily, when I ask how familiar he was with the programme before he started working on it – and there’s no suggestion that he’s aware he’s riffing on one of the show’s most iconic lines.

But no Game of Thrones cast member can have great job security. “Who was it who said, ‘There’s only two things you can be sure of in life, death and taxes’? he jokes. “Well, there’s a third thing, which is your character death in Game of Thrones.” A recurring cast member throughout seasons four to six, Ashton-Griffiths was killed off in a shock terror attack in the finale of the most recent season. I chatted to him about the strange experience of being killed off on the biggest show on TV.

How much did you know about the show before you started working on it?

I knew there was a thing called Game of Thrones and I’d been up for a couple of parts in earlier seasons. Beyond that, I knew nothing.

Can you tell us which ones?

Well, without obfuscation no, in one case, because I can’t remember! The other part in the first season was I think the one that Roger Allam took [Illyrio Mopatis]. I then declined to audition for a third, because I didn’t think it was worth auditioning for: the High Septon [Paul Bentley]. I didn’t think that was good enough so I declined to go out for it. And I think I was right.

So what happened when you auditioned for Mace?

I auditioned in the ordinary way. I remember at the audition getting Tyrion and Tywin’s names mixed up, and they had to correct me and stop me, so we went back and did it again.

But it didn’t put them off, obviously, because you got the part.

Well, then I got cast. And I thought, “Right, okay, good.” And then the shit hit the fan, and there was loads of stuff in the press, blogs and stuff appearing online about how awful my casting was: people saying, “it’s inappropriate” or “it’s just not what I imagined.” Inane comments you see at the bottom of pieces.

How long was there before being cast and starting filming?

I think I was cast on the Tuesday, I was in Belfast for costume fittings on Thursday, and back in Belfast on the Monday to start work. It was a very quick turnaround. So I turned up on the first morning, not really knowing what I had let myself in for, and the first thing I shot was the trial of Tyrion Lannister [Peter Dinklage], where I was a co-judge with Tywin Lannister [Charles Dance] and Oberyn Martell [Pedro Pascal]. I had expected there would be some sort of introductory booklet, explaining that these are the characters, this is where we’re at. But no, it was basically, “Oh, do come in, you’re sitting there.”

Oh, God…

So I just said the lines, but I was thinking, “I don’t really understand any of this...” I didn’t know that Tyrion’s father was my co-judge, or that this nasty girl giving evidence against him was his sister. I had no idea! I said to Pedro during a break, “Why has he [Jamie Lannister] got a gold hand?” He fell of his stool laughing; he thought it was the funniest thing he had ever heard. So, realising that things were afoot, I went to the production office and said, “Have you got any material for me, something I could look at? Just because I have no idea what’s going on!” This was towards the end of the first week, and they gave me the box set of Season Two, which I duly watched, and it was like “Ah….” Season Two is okay, if you want to get a sense of the relationships, you can work out who’s who from that, the thing is – and who knew! – Season One is the place to start.

I didn’t really understand the consequences of this. I was in Karachi a few months later doing an interview for Dawn, the English-speaking newspaper there. I told them all this story and all these comments appeared, hundreds of them, nasty, vicious little comments about “cheapskate bastard”, or “If I’d been cast I would have watched the whole thing, there’s only 30 hours to watch.” The thing is, I’d just finished a film with Woody Allen in which I wasn’t allowed to see the script. And just before, I’d done a film with Mike Leigh in which there was no script, and the character developed. It’s not about knowing or not knowing anything, because, of course, the character never really knows what other people’s motivations are. So there is a Woody Allen-like justification for not letting people see the script.

Your character first appears to the viewer in “The Lion and the Rose”, also known as The Purple Wedding, which is a pretty intense episode to be introduced in!

The Purple Wedding was a huge shoot; it took at least a week, possibly more, to film. But by then, we had already shot the trial scenes. I had certainly seen all of Season Two by then. I’d made friends with everyone by then. Before that we shot the actual wedding in the Sept, and before that the gift-giving scene where I present Joffrey [Jack Gleeson] with a goblet. The thing I remember about the goblet scene was a technical fall-out between me and the props people, who kept putting it down in a certain way. [He demonstrates at length with his coffee cup.] It’s not rocket science really! But that’s a separate technical tale of acting, that’s the sort of japes we get up to!

The wedding was where I met Diana [Rigg] for the first time, then we all went to Dubrovnik, and we were all there as a company because big things were happening. It was great, actually.

Did your performance change after you gained more knowledge of the series? Mace is nicknamed “oaf” and people are quite mean about his intelligence: so perhaps not?

Well, I often wonder whether I have sufficient range as an actor for my performance in that trial scene to have been any different had I known what was going on! I don’t know the answer to that. But I did relax more into it, and I had a better sense of the other characters and their social positions within it, who you are superior to, and therefore how you react to them.

Do the royal cast members on Thrones only socialise with each other?

It’s quite well-recorded that if you have a group of actors and put them in military uniforms, during the tea breaks they often tend to sit together. And you do kind of fall into... It kind of does happen, yes! I knew Lena Headey [Cersei Lannister] quite well, I’d worked with Charles Dance [Tywin Lannister] before.

Of course, lots of the people I met I last saw in Season Four, when we were shooting the Purple Wedding! I’ve not seen Peter [Dinklage] since, nor Connleth [Hill, Lord Varys].... So you get to see these nice, good people, and then you just don’t see them, because they’re in Meereen. On the other hand, while I had no scenes at the Wall, with any of the [he does a Jon Snow voice] Knieeeeghts Waaaatch, they did all hang around the bar at the hotel in Belfast, so Kit [Harrington] and I used to sit around drinking beers together.

They’ve all got that accent because Sean Bean refused not to do his own Northern accent, so they all had to do Seaaan Beeeean. That’s what’s going on there. But Kit of course has a rather refined home counties thing, he’s not Noooortthherrnnnn at all. They all sound like Simon Armitage, it’s hilarious.

How did being in Game of Thrones differ from other jobs you worked on?

The thing that’s different about being in Game of Thrones, compared to anything else, is that it’s got this extraordinary following. And I think it probably has something to do with semiology, and making meanings from things which aren’t there. Somehow in Thrones, the viewer makes more of it, there’s something very strange about it. That was what I wasn’t expecting, and that was the curious part of the process.

The other critical thing about Thrones, one of the things that makes it special (and this is about money, ultimately), is that it’s one of the few things I’ve been on where you get the perfect conjunction of intention, ability and resource: they really want to do it well, they really know how to do it well, and they’ve got the money to do it well. Often you get two out of three, but not all three in the same place.

How did Mace develop as your performance moved through the series?

I think one thing nobody predicted was the great sense of homeliness that came out of this character, how much he cared for his children: that is what mattered to him more than anything else, which ultimately made his end so telling, that he went with his children.

David and Dan [co-creators David Benioff & D.B. Weiss] are very good, they get just the right number of parties in as well, so whilst you’re away in Dubrovnik shooting, they throw a party on the beach - it just keeps people happy, and they’re really fun. And I was chatting with Dan at one of these parties, and I happened to mention that my career started as an opera singer. And he went, “Oh, really? Where?” and I said, “English National Opera,” and he went, “Oh, how interesting,” and we moved on. Next season there’s a scene written for me as a singer!

I remember, in Bravos, to the bank manager!

It was unexpected, but it’s organically perfect, because it meant that Meryn Trant [Ian Beattie] the mad Kingsguard, they could then pull focus onto him infuriated, saying, “Who is this utter twat singing?” so he can go off and murder girls instead. Nothing is wasted, nothing’s superfluous. If it’s there, there’s a reason for it.

What was the song itself?

There were words written, and I said, “Oh, I’ll write my own tune, shall I?” Which I duly did. But for reasons which are difficult to really grasp, the composer decided that he needed to have done it. And this is to do with contracts... I thought my version was rather better, to be honest, and I’ve still got my copy to prove it! They were in touch with my agent talking about release rights and music and arguing with her, and she phoned me up and said, “Is it going to become a hit, this song?” and I said, “No! It’s just eight bars of nothing!” So the composer’s getting very upset that someone else’s music might be in it.

The interesting thing about Westeros as a space is that it has no classical antecedents. One of the great geniuses of the work is that it creates a heterotopic space that has never been seen before. Because of that, there’s a sense that the music can’t be recognisably anything, which is very difficult, and I think there’s a principle that if there’s any music in it at all it must be the composer’s. It wouldn’t have made much difference, let’s be quite clear about it, and there is an outtake of me singing my version in one take because I just got it wrong and started singing my tune!

Are you sure that was an accident?

It genuinely was! And Mark Gatiss said, “Well, what the hell was that?!”

When did you know you were going to be killed off?

David and Dan are well known for their habit of phoning everyone who is gonna die in the coming season. They phone in March/April. So I got the call, and I knew what it was, I was sitting quite happily watching television at home. Dan called. “Hi Roger... oh, man..” And I’m like “I know what this phone call is.” And he’s like “Yeah...” And I said, “Well, is it a good end?” and he said, “Well I think it’ll be okay.” And I was out! I didn’t actually know the details until I got the script.

How did you feel about the scene itself? Dying in a mass terrorist attack is quite a way to go!

Who was it who said, “There’s only two things you can be sure of in life, death and taxes”? Well, there’s a third thing, which is your character death in Game of Thrones. I had hoped my character’s TV path would reflect more closely his book path. So I had expectations, which were... dumped on. But I thought it was a pretty good end, and in a glass half full sort of way, I was grateful to be part of this extraordinary machine. I think, like most people who go out, I thought it would have been very nice to stay, and do more, because it was just such an enjoyable job. I had even found the beauty in Belfast by the time I finished shooting - though it took me a while!

What was it like filming your character’s final scene?

My death scene took, I think, four days to shoot, which was particularly demanding because my characters was in a heightened emotional state, which meant I had to be in a heightened emotional state for four days! It can be sort of relentless.

Was the final day of that scene emotional? It obviously wasn’t just your last day.

It was the last scene we filmed, but some of us had to go back - Ian Gelder [Kevan Lannister] I know had to go back and do more later. But I remember that Ian Gelder, Jonathan Pryce [The High Sparrow], Natalie Dormer and me travelled back together. This is how sentimental we were about it: we rushed to get out of costume so that we could go straight to the airport and get the early flight. We sat in the BA lounge at Belfast City Airport drinking champagne, quite a lot of it. Natalie at the time had a Gold BA Card, and she sort of wielded it around - we all had a BA Card of some kind, but hers was Gold.

What has it been like since leaving?

One of the things that Thrones and all shows have in common is that once you’re out, you’re out. I don’t get the newsletter, I don’t get invited to get-togethers, I’m just gone. You’re out, you cease to be part of it. Even if you still feel part of it. I’ve always likened being an actor to being a plant with no roots, so if I rocked up now on a set with half a dozen actors I didn’t know before, by the end of the day, we’d be best buddies, in the bar, having a glass of wine, for sure. But then we’d go away and never see each other again. And Thrones is just like that.

But you still go to Game of Thrones fan conventions?

Yes! They are very intense, so it takes an adjustment. You should never take it lightly. I met one fan, a very withdrawn and shy boy, whose mother had to make the introductions for him, but the last time I saw him, he came over on his own! Another girl I spoke to commented that I had changed her life when I told her to ditch her university course that she wasn’t enjoying and do what she wanted. It’s a tremendous responsibility, and you suddenly realise that there is some power in celebrity. You don’t get any training for that. Some people, for maybe no good reason at all, will listen to you, particularly the people that come to these comic cons.

But the thing about the community of people who come to these events is that they are supportive and loving and they welcome people in. It’s a place where anyone can have a safe and fun weekend. I’ve seen “Steampunk Minions”. At one event, I saw a man dressed as Darth Vader, but his costume was made entirely out of twisted balloons. And his cape billowed out behind him. But the extraordinary thing was, no one popped one. No one. He was completely respected for what he’d done, for this achievement. It was magical. Nowhere else in the world can you find such complete, uncritical acceptance.

Has your career changed since Thrones?

Well, no, other than that overnight I became a “senior” and “noted” and “veteran” actor. Of course, inside, I’m young, I’m waiting to blossom, I’m waiting for them to offer me Bond! But there’s always an element of Emperor’s clothing in this business. We can all act, but on top of that, if you’re a “noted” and “veteran” actor in Game of Thrones, there’s no dispute that you can act.

So now you’re on our screens in Taboo with Tom Hardy. How is that? You’ve been reunited with Jonathan Pryce.

I turned up on the first day, and he was like “Oh, bloody hell, I thought I got rid of you!” It was cast by the same casting director. At the read through on the first day there was me, Jonathan, and Oona Chaplin [Game of Thrones’s Talisa Maegyr]. And I’d not met Oona on Thrones at all, but it didn’t matter, we were all Thrones actors, so there was a bit of that going on. But I don’t think I’m going to be attending a Taboo convention any time soon.

Is Tom Hardy an intense presence on set?

Tom Hardy is remarkable. He’s the only man I know who takes his shirt off in the make-up truck voluntarily. But then, frankly, if I looked like that, I would too. And he’s very good at what he does, and it’s his project. But he’s just one of the boys. He was [he does an East End accent] giving it all this on set one day, and I said, “Where are you from, Tom?” and he said, “Sheen, but don’t tell anyone!” There are some stars who change, but Tom isn’t one of them.