Graham Kibble-White gets up close and personal with Zoe Wanamaker...
Zoe Wanamaker is nervous.
Wearing a pale blue high-necked sweater and a trim grey suit, she's using a small rolling machine to assemble a brown cigarette. With sharp, birdlike movements, she completes the job, lights up and puffs away.
She's clearly uncomfortable about the prospect of being interviewed, but submits to the process with grace, thoughtful pauses occasionally interrupting the flow of conversation as she ponders long and hard over her answers.
"I haven't seen it at all," she says, when asked what she thinks of Cards On The Table, the Poirot mystery she stars in.
"I don't like watching myself," she continues. "I start looking at stuff that I really shouldn't be, thinking, 'I ought not to be standing like that, I wish I'd done it this way' and so on.
"I'm constantly criticising myself - 'Oh my God, do I really look like that? Look at my mouth!' - so I just end up up my own backside really. Then what happens is I find I restrict myself when I start to do another job. I've become too self-conscious."
Thankfully, such introspection didn't mar her performance as eccentric crime writer Ariadne Oliver, a much-cherished creation from Agatha Christie, and something of a foil for the sometimes pompous Belgian detective.
"I don't think there's any other character who sends Poirot up like she does," smiles the 56-year-old actress.
In a similar vein, Zoe also enjoys keeping Poirot's alter ego, David Suchet, on his toes.
"I tease him a lot," she laughs, "and I think he needs it. There's this thing about the funny little voice he does, and I just make sure he doesn't take it all too seriously. When you indulge in something like this, you can get into it completely, so sometimes you have to be reminded that it's just Zoe and David."
The duo have a long friendship that dates back over 30 years.
"I worked with him in 1979 on a play Once In A Lifetime," she reveals, "but I knew him long before that. We enjoyed working with each other a lot during that period and so I think he was a little instrumental in getting me this role.
"Scanning through all the Christie books Ariadne appears in, I picked up that the character is completely unlike me. She's a big woman, like a battleship.
"David wears lots of padding as Poirot, but I decided I was not going to go down that route because it's restricting and hot. He has to stand in front of an air-conditioner a lot, like a penguin.
"Instead I decided I'd wear something small that gives you a feeling of being substantial, so the costume designer found this transvestite shop which sold fake breasts.
"They were called 'medium beauties', and they were really good. We could have had 'super beauties', but I think I would have looked like Margaret Rutherford in them.
"I was sorry to part with them at the end, because I've never had tits before. It was great. A new thing for me."
Some people think that in Ariadne, Christie was writing about herself.
"Could be," says Zoe thoughtfully. "I think she sends herself up a lot with the character. In Cards On The Table there's a section about how difficult she finds it to write her crime books, and how she's given herself the most ludicrous detective, this Finn called Sven Hjerson, and she knows nothing about him. Nothing.
"As soon as she's finished writing one novel, she starts another one, even though she hates doing it."
Unbeknown to Zoe when she accepted the role, Ariadne has a strong band of fans who've keenly followed her adventures across seven novels and one short story collection.
"An old friend rang me from New York, and when I said I was playing Ariadne she became so excited. I realised then I was stepping into a world that I knew nothing of. But she's a prime character for a woman to play."
Talking of prime characters, last year Zoe notched up something of an honour by portraying the first new monster to menace Doctor Who following the series' triumphant return to BBC One.
The good news is, her character, Cassandra, will be back for a rematch when the show returns to our screens in the spring.
"It's fabulous!" she enthuses, when asked what it's like to be a 'Who baddy. "It's such fun. It's such a credit to Russell T Davies and the producers. I think what they've achieved is brilliant.
"I think Cassandra's a naughty, naughty girl. That's what's such fun about her. She's cheeky. She's not evil, she's just naughty."
Alas, she's sworn to secrecy when it comes to talking about just what the vain "last human alive" gets up to this time around, but she is prepared to reflect upon what the role means to her.
"It's like being a baddie in a Bond film," she muses. "It's that sort of television equivalent, I think.
"I desperately wanted her to come back. It's a character you can bring something to, twist it around and make something funny.
"She reminded me of Joan Rivers and that extraordinary woman who changed her face a million times to look like some sort of tiger.
"And it was extremely witty to do. After so many plastic surgeons, liposuction and all that she's ended up just a flat piece of parchment. I think that's fabulous. A fantastic invention.
"That's the best thing about science fiction, it's basically fairy stories come to life, but they're great fun.
* The Belgian sleuth meets crime writer Ariadne Oliver in Agatha Christie's Poirot on ITV1, on Sunday at 9pm