Since we first met seven years ago, Billie Piper has remarried, become a mother and, also, grown into a ridiculously accomplished actress, stage now as well as screen. It will be a while, however, before anything out-paragraphs Rose Tyler in her Wikipedia entry.

This is no sneer: how many other young “companions” in Doctor Who have, through dint of their talent, stayed famous? It does, however, mean that Piper has a doctorate in dissimulation. Such was the BBC’s paranoia about spoilers that the prelude to every one of Rose’s many comebacks on the show was a fierce denial by Piper that she would ever reprise the role.

“Shameless. I mean, it was lying to people’s faces daily and loving every minute of it,” she says in a studio near Waterloo, after a photoshoot bravely borne despite a heavy spring cold.

Caveat emptor, then, dear reader, especially as Piper wrote in her 2006 autobiography that anorexics (of which she was one: a teenage pop siren stuffing tissues into her mouth) are “accomplished liars”. Yet this afternoon she appears playfully, almost recklessly, candid.

For instance, I tell her that I admire her taste in husbands, the Radio 2 breakfast show host Chris Evans and Laurence Fox, Hathaway inLewis. They remain two of my favourite interviewees, unusually likeable and generous with their answers. They could not, however, I suggest, be more different: the ginger nut so, well, nutty; Lozza so public-school laid-back.

“So laid-back?” she replies astonished. “No. If you asked any of his friends, I don’t think they’d use words like ‘relaxed’ or ‘laid-back’ – but it’s good that you thought so. Maybe he was just incredibly comfortable that day. He certainly knows who he is, and that’s quite relaxing to be around. I’ve never met anyone who’s so loyal to what they believe and so knowing of who they are, what they are able to do and what they’re not able to do.”

He doesn’t seem ambitious.

“He’s not. He’s rare in that way. It’s so nice to be around a male actor who isn’t ruled by the need for success and adoration. He’s just not wired that way, and he has very strong family values. He’s a really rare beast.”

But not relaxed? Surely next to Chris?

“Chris is hyper. I get what you mean. Laurence’s energy is quite steady, isn’t it? And Chris is very charged. But, you know, Laurence gets wound up about things. He’s highly strung in his way. Or maybe I see that in him because I bring that out in him. Maybe I encourage that behaviour.”

Do you annoy him?

“Frequently. Frequently. And he annoys me. You know, it’s far from perfect.” She pauses. “But it’s also great.”

I bet he is annoying.

“We’re all annoying! The kids are annoying. The dog’s annoying. Suddenly, I hate the dog. I do shout at them, but I’m quite shouty anyway, in general.”

Her candour reaches its limits only when we move on to talk about the return of Sky Atlantic’s Penny Dreadful, a fantasy show just as jealous of its secrets as Doctor Who. Indeed, secrecy is why you are reading this piece days after, rather than days before, the transmission of the first episode of series two. Penned by John Logan, it is a mashup of gothic horror fiction and Victoriana: seances, vampires, Victor Frankenstein and Dorian Gray, done in great earnest, with tons of sex and the production values that befit an American co-production. Fans will know by now (and therefore I am licensed to report) that Piper’s character, Brona Croft, who spent the first season dying of consumption in the backstreets of Victorian London, is back. Or rather her body is back, stitched up and reanimated by Frankenstein into a potential bride for his first creation, Caliban, as played by Rory Kinnear.

My bet is that Piper’s refined new incarnation does not really fancy Caliban.

“Why? Why would you say that?”

Because he’s so ugly and weird.

“He’s definitely peculiar, but he’s well read and strong, and who doesn’t like those two things in a man? He can recite poetry,” she counters. Piper’s taste in husbands is clearly an elastic thing.

In any case, it is farewell to Brona and her impenetrably authentic Ulster accent, replaced (spoiler alert) by something much nearer Piper’s own RP, a product not of her working-class upbringing in Swindon but Sylvia Young Theatre School in London. Brona, poor thing, was a member of the oldest profession, as was Belle, Piper’s second most famous incarnation, in ITV2’s popular Secret Diary of a Call Girl. Last year she played a prostitute again in Sky Arts’ one-offFoxtrot by Polly Stenham.

“She wasn’t a prostitute.”

What was she?

“A stripper with benefits, I suppose.”

Why do you play these women?

“I don’t know. It’s peculiar, isn’t it? Maybe it’s because I’m not scared of it, and I’ll do it. Maybe they think, ‘She loves it! Line ’em up. Who could we get to play this prostitute? Billie Piper!’ I think I am going to have to call it a day. On Penny Dreadful, my days of whoring have at least come to an end, sadly.”

Have you hung up your …?

“Pants. I don’t know. I think I should stay clear now, although the other thing is, I do find people who don’t live in a conventional way interesting. I find I’m always more drawn to the parts that are challenged or complicated or weak or mad, rather than girlfriend roles.”

Well, look at you, I say: there has been nothing straightforward about your life.

Aged 12, she left home to board with a great aunt and uncle in London and attend Sylvia Young. By 15, she had been spotted by a pop impresario, fashioned into an English Britney and had a No 1 hit, Because We Want To. By 16, alone, mid-tour in a hotel room in Chicago, she was so unhappy she contemplated swallowing the contents of a bottle of melatonin. She rang home and told her parents she wanted to kill herself. When she returned, however, it was not to them but to a flat in London with her soon to be fiancé, but never to be husband, Ritchie Neville, from the group 5ive. For a while, after her parents, Mandy and Paul, sold their story to the press, she stopped talking to them altogether. When, at 18, she decided to marry the 34-year-old and, at the time, notorious DJ Chris Evans, she did not even phone them.

“I’ve always been a bit fractious with my parents,” she explains. “But I think that’s because I left home in my formative years and I didn’t really know how to be around them. I was making really big personal choices at a very young age, and I kind of forced them out of my life, because they were the only ones telling me to calm down and watch what I was doing and who I was with – all that stuff that just seemed really boring. Since I had the reins at an age that was way too young to be independent, I didn’t really respect them enough, to be honest. But also, with big, strong personalities, we’ll always tussle. We all do in our family. We’ll scrap for a bit and then not speak for a while, but it’s all repairable.”

Now, however, her mother spends plenty of time with Piper, her husband and their two children, at their home in north London. “I think when you have your own children, you see your mother in a whole new light. It’s a wonderful thing to experience later in life, that feeling of how much respect and appreciation you have for your mum, and how selfless they were – far more selfless than maybe we are as modern women.”

The problem, I say, was surely that she was a teenager trying to cope with both the adult problems of stardom and the adolescent one of growing up, finding a distance from her parents. Who would have coped?

“I was certainly quite wayward at that age and very, very headstrong, without any emotional tools, really. But, you know, that’s it. It’s done. And I will try hard to redeem myself to my mother, for my mother.”

She is 32 and has 2 sons, Winston, 6, and Eugene, 3. Unlike her mother, a shop assistant, Piper went back to work relatively quickly after having each child. In the past five years she has earned a reputation as a formidable stage actor in three plays: Reasons to Be Pretty at the Almeida, The Effect at the National and, last summer, playing a Rebekah Brooks-esque character in the newspaper satireGreat Britain. Having seen two of those performances, I can attest to her charisma and technique. Yet she has also had to play the even more demanding role of parent.

“It’s funny, isn’t it? Raising children now, it feels as if you’re told to ignore every part of their behaviour. ‘Don’t let them see you sad. Don’t let them see you fight. Don’t let see them see you riled up or impatient or greedy or neglectful. Don’t let them see anything.’ So I blow my top and behave quite differently.”

Does she ever slap them? “Oh, no! And the only reason I don’t slap them is because I couldn’t handle the guilt. And I don’t do it because I feel as if it would be me having run out of ideas to raise my children: ‘I’ll just slap them.’ But it’s also me being a victim of our time – feeling as if I don’t want to be judged, if I’m really honest, as well. It’s lots of those things, but mostly I don’t want to be sitting in bed thinking how awful I was to smack my kid and how scared they must feel.”

She had always wanted to be a mother. Yet parenthood has changed her in ways she did not expect. For instance, she is much less sure than she was of what she thinks of – to get back to that – prostitution, despite talking to call girls in preparation for playing Belle (including the real Belle, Brooke Magnanti) – many of whom spoke of the trade as empowering.

“When you have children, your thoughts on the world change quite enormously, and something you used to think was fine or you could understand, suddenly becomes vehemently quite different.”

I wonder, then, how long it will be tenable, as a mother, to film sex scenes as explicit as hers in Penny Dreadful.

“I am tiring of sex scenes. It’s about time, I have to say. But I’m only tiring of them because you suddenly have to become quite body-conscious. Filming them is so artificial that it’s borderline hilarious. I mean, your biggest challenge is not laughing. I don’t see myself as a sexual person, so I don’t find me being naked around men hard – unless it is me lying still on a slab, trying not to laugh.”

I confess that even in Secret Diary it seemed slightly ridiculous that people put so much expense and elaboration into their sex lives.

“We’re talking like parents of young children, aren’t we?” she counters. “I don’t mind swanning around naked. I don’t see myself as a sexual being …”

Yet some people are obsessed by sex.

“More people than not, probably. But not parents of young children. We’ll rule those out.”

John Logan, Penny Dreadful’s creator, has also co-written the next Bond movie, Spectre, so I feel emboldened to ask if she might be tempted, before she entirely says goodbye to nudity, to play a Bond girl.

“I’m not that material. I would feel very self-conscious playing a Bond girl.”

Why? “I don’t know. Because I’m not that kind of …” Not that kind of girl? “I’m not that kind of girl.”

I’d say you are exactly that type of girl.

“I don’t think I could move through scenes in that way. I don’t think I have the grace or the poise of a Bond girl. I think I’m slightly more crooked and weird. You have to have perfect symmetry to be one of those women.”

Her Penny Dreadful co-star Eva Green was one in Casino Royale. “She’s got perfect symmetry. I don’t. I’m weird-looking.”

What about your appearance don’t you like? “Oh gosh, well, there’s less now because you just get used to what you’ve got, don’t you? You realise that there are things about you that you cannot change, so you just get on with it, but, I mean, there’s loads.”

Give me one example. “I hate the way that I suddenly develop rosacea, not that you’d see it under this mask [of slap].”

This is the grown-up acne, is it? “I get that as well. I feel like one of my eyes is becoming quite lazy. That’s become my new obsession. My feet should be caged. They are just rotten. They’re the kind of thing they put in cages in Victorian times and people would pay good money to see them.”

Why? “They’re hoof-like – a lot of sole and just wrecked from dancing. That’s what I like to say, but it’s actually a genetic flaw. It’s my mother’s fault. I’ll rage at her. And my nan; she also has horrible feet. I mean, the best shoe for us would be Crocs, but, of course, they’re not socially acceptable.”

I cannot believe that many men have noticed these defects – certainly not her first husband, Evans, who met Piper in 2000 on his chat show, TFI Friday (due for a one-off 20th anniversary revival in June). In his memoir he describes her as the “human equivalent of platinum” and “more alive” than anyone he had ever met. The volume, a narrative of Evans’ return to sanity and relative sobriety, gives emphasis to the curative powers of his relationship with her and their low-alcohol, healthy-eating sojourn in California as thirtysomething man and child bride.

Although when I interviewed him five years ago, he disagreed with me that she was the heroine of the book, and cited other girlfriends as contenders for that role, theirs remains a fairy-tale divorce. They drifted apart when she filmed the first season of Doctor Who in Cardiff. Upset at first, she grew to accept that he was right when he said they were ceasing to be “us”, and brooked no thought of a financial settlement from him. They were guests at each other’s next weddings: his to golfer Natasha Shishmanian; hers to Fox.

I met Fox at their cottage in Sussex (now sold) not long after their wedding, in 2007. He was still marvelling at his luck. “It was like that,” he said, clicking his fingers. “People go, ‘When you know, you know.’ It’s so true. You just do. You just go, ‘Wow, yeah! Yes please, and thank you.’ And it’s the best.” His left wrist was freshly tattooed with “Mrs Fox 31-12-07”, a memento of their honeymoon in Mexico.

Since then, it sounds as if romance has turned into the touchingly normal hard work required of a good marriage, something Evans, and perhaps Piper, were not at the time up for with each other. There is one thing I do have to ask, however. When I saw her beforeSecret Diary, I was concerned she was looking so thin when stripped down for action as Belle. She explained she had to keep her weight down for the part, but had also admitted to an anorexic relapse after the Evans marriage ended in 2004. “These things are always standing in the shadows, lurking,” she told me. “I don’t think they ever completely go away.”

I am reassured to see that there seems to be a bit more of her today beneath her Camden Market jumper. Is the anorexia still “lurking”? She congratulates herself on the “dramatic” quote she gave me.

“It doesn’t really lurk. Also, you’re doing a lot when you’ve got kids. This sounds like one of those ‘My relationship with my children’ pieces suddenly, but you don’t have a lot of time to think recklessly or obsessively about yourself. And that’s great. So much more liberating. I don’t worry about those things now.”

Do you even have scales in the house?

“No,” she says. Interesting, I say. There’s a guilty pause.

“No, I do have scales at my house. That was a lie.”

But do you look at them?

“I will use them now and again. But my obsession with things like that has really tailed off, thank God.”

And I believe her, for a lie willingly exposed by the liar is no lie at all. Never mind the rebirth of Brona Croft. The reinvention of the challenged and complicated wild child Billie Piper as a yummy yet shouty mummy and, let us never forget, exquisite leading actress, has been a success.

Penny Dreadful is on Tuesdays on Sky Atlantic