If performing ever gets boring for Gemma Whelan, MI6 could well be an option. She's become something of an expert at keeping stuff hush-hush.

Not only is the impressively flexible actress/comic a recurring character in arguably the most spoiler-sensitive TV show ever, Game Of Thrones (we do know that her ironborn warrior, Yara Greyjoy, reappears in the forthcoming Series 6), but she also has a still fairly under-wraps TV vehicle on the cards, fingers crossed: a chat show hosted by her buttoned-up but curiously broadminded creation, Chastity Butterworth. As for the intriguing supporting cast... she's keeping mum, but there may be some free tickets left, if you're quick.

The secretive projects keep on coming. On the Sunday our interview was due to happen, Whelan was suddenly whisked off for talks about another potentially exciting new role, which she couldn't tell us anything about, at all. Still, admirably unaffected by all this, she took the call and was actually strapped into a plane seat awaiting take-off while we talked, which is definitely a Circuit Training first.

Let's begin with the blush-inducing Ms Butterworth...

How's it going with the Chastity chat show?

We're at the stage now where we've been given some money by the BBC, and the producers are chipping in as well. So we're doing what would've been called a read-through, but we're doing a whole [live] show. We're going to give them everything, throw everything at it - because everyone seems to really believe in it, which is nice.

So we're sort of at the stage where everyone's really interested and excited, but nothing's happened. That limbo-land, where they could commission a pilot or a series, but we've got to show them what we've got first. Peddle our wares a little bit.

It must feel like auditioning?

Exactly, but it's not just on your shoulders, its everyone else who's thrown money into it and produced it and helped you write it. No pressure!

Presumably you've got the show all worked out by now?

I think so, we've got some more meetings, well, tomorrow - they're meeting without me, as I'm going to be away. Then Tuesday we're working, then Wednesday I fly off for Game Of Thrones, so it's a bonkers week. Basically we're writing in every single nook and cranny that we can. But everything's in good shape. I've got some very good people helping me.

I believe the very funny Mike Wozniak is involved?

Yep, Mike Wozniak is going to be playing my butler. And I won't say who it is as it'll ruin It, but I've got an amazing actress playing my mother, and an incredible guest, who asked me if they could be in it, which is a real compliment. It's a very exciting guest - I'm not just spinning, he really is! So yeah, excited to do it - but nervous, terrified as well.

I remember a couple of years ago in Edinburgh, you doing a serious play then having to run straight across towadn to do Chastity - you're used to that shift of tone...

Yeah, I felt that was good training, sort of by accident. So I'll be Yara Greyjoy on Wednesday, then Chastity Butterworth: very different characters.

They're pretty much polar opposites. As an actor that must be the dream, to mix it up like that.

It's really nice. Often what happens is, you get... not typecast, but they'll think 'that's the go-to person for that sort of thing, and that's the go-to person for that sort of thing.'

It's just serendipitous timing. I would never have got my audition for Game Of Thrones if I hadn't been in an audition for a comedy: the casting director just happened to think I might be right for this other thing [GoT], otherwise I would never have the opportunity to exercise those muscles, more serious acting.

So yeah, it's pretty cool to be able to do both - or not to be 'able' to, to be allowed to. Because I think a lot of actors and actresses can but aren't given the chance.

So we actually met at a festival launch a few years back, when the PR I was with ran over like a teenage fangirl...

That's right! In Camden wasn't it - the launch. Do you remember we got free toilet rolls in the goody bag? That festival never happened you know.

They must have spent all the money on...

Toilet rolls!

Exactly. I imagine you get that sort of reaction a lot - at places like airports.

No, I never get recognised, or very rarely. The last time I got recognised was by a woman who worked in a station café in Preston about a month ago - she didn't say anything, she just tweeted about it afterwards. So no - thankfully I look quite different to Yara Greyjoy in real life. I hope.

It's not such a bad thing. When I go out with Alfie [Allen] and those guys, from the show, they just get hounded. Obviously it's wonderful that they're such good actors and they're doing so well, but there's no privacy.

It's pretty barmy with Thrones - I remember seeing a newspaper story a few months back about you being spotted in Northern Ireland, so Yara was clearly back in it. You must all be like a sleeper cell, trying not to reveal anything.

Absolutely - even when I said I'm going to Northern Ireland on Wednesday to you just now, I thought 'oh god, maybe I shouldn't say that.' You really watch your back on everything - 'don't say too much'. But at least it's been leaked that I'm going to be in it, so I can talk freely about that.

So the shows are off the books now?
Yeah, they've sort of... not run out of books really, but they've liaised with George RR Martin who writes the books, and gone off on their tangent, with his approval. So that's why people are even more interested in spoilers. It's funny isn't it, there's no other show like it.

It must be even more nerve-wracking for you guys getting the scripts, with no idea what's going to happen.

Exactly, when you're scanning through [frantically] 'Am I dead? Am I dead? Am I dead?' - it's the first thing you look for.

If I got written out, I'd go and hang around at Belfast airport anyway...

To confuse people! Although hopefully you'd have more good things to do at the time.

So have you done regular stand-up, as yourself?

You know what, I started doing stand-up; I did the university gigs initially, I did a stand-up course on my university course, a few gigs as myself. Then Janie Jenkins, who's now my agent, came to see me at one gig, and said "there's something a bit Jane Austen about you, why don't you push that more, the incongruity would be really funny." So it was her suggestion that pushed me into trying character. But yeah, I have done straight, and I do compere as myself as well, which I quite enjoy.

I always think that you only realise what a skill compering is when you see someone who can't do it. Does it come pretty easily to you?

No, it's something I'm trying to work on, I'm not a natural. But you're absolutely right, it's a real skill not to just do a 20 minute set; to talk to the audience, do some quick one-liners, improvise around it. My boyfriend's brilliant at it [CT was too polite to enquire further], I'm not so good. I'll keep working at it.

I didn't realise you were in [infamous sitcom flop] The Persuasionists!

Ha, yes I was. I was the second office person from the left and my character would change each week depending on who needed to say what line. So one week I was really passive aggressive and the next week I was really dumb, but I was still called Josephine. It was a glorified extra role, but with a name and everything. We all quite liked each other on that job so I just kept going back in to say a line here and there.

There were some great people in it...

There were amazing people on there, who've gone on to do brilliant things, and had already done brilliant things. But that one just didn't quite fit.

Adam Buxton wrote a very funny long response when I emailed him about it: "When you're involved with something that successful it changes you..."

Ah, it was a really good fun job. You always learn something, don't you?

Back to Chastity, and I suppose there is a link with Yara: filth!

That's true - either cheeky or elaborate. There are certain things you wouldn't want your mum and dad to watch. Although my mum and dad love it, they love Thrones and they love Chastity, although my mum was like "darling, what's 'the safe word?'" - asking all these questions. And certain other things I can't say here because there are people around. Certain Japanese practises.

I know the one you mean.

There are things I've had to explain to my mother over the years, which she's revelled in gleefully, how naughty it is. That's why we've got a mother character in the chat show because my mum's like that.

It's a bit Julian Clary, rudeness-wise...

It is isn't it - it's all as camp as Christmas really, as camp and innuendo-filled as possible, that's what we want.

...but oddly innocent too.

Chastity gets away with it, she asks the questions that no-one else asks, but hopefully the joke will always be on her. It's not going to be malicious at all.

So is there a whole Chastity backstory? How old is she?

She's my age. We're sort of working it out, that she's the result of a one-night stand, with a very embarrassing mother who keeps cropping up at inopportune moments, but she's married well, to Horace Butterworth, who we never see. He's always upstairs listening to his Barbara Streisand back catalogue.

Do you know the potential timescale, if a series does get commissioned?

I actually don't, I'm a bit of a day-by-day person, I try not to think too far ahead or I'll either get excited or disappointed. So I'm trying not to attach an outcome or an expectation to it.

It's always hard to predict which projects will do well...

Yeah, you'll have an absolutely brilliant idea that doesn't go, then one that you think 'well this is never going to get anywhere' absolutely flies. It just depends on where the gaps are in their perceived market I suppose. At least if it doesn't happen I know that we threw everything at it and gave it our all. People seem excited.

At least there are other options now - Stewart Lee admitted that the BBC weren't going to re-commission his Comedy Vehicle until Sky offered to take it.

That happens quite a lot now doesn't it, 'oh well, we'll go to Netflix or whatever.' But that's a luxury if you can do that, someone like Stewart Lee - certainly I'm not in that position yet.

So have other people on this flight clocked who you are, from this conversation - hours of people hassling you for Thrones gossip ahead?

No, I don't think so. I'm actually going to work on the Chastity script now, because I'm missing tomorrow, out of respect to the people who are working very hard on my behalf. I'll throw my tuppenceworth in, for what it's worth.

Chastity Butterworth's Chat Show is at the Soho Theatre the 27th October 2015. Free Tickets