National treasure is an overused phrase, but one that’s impossible to shut out of your brain when meeting Helena Bonham Carter. Wearing a cleavage-heaving jacket and waistcoat by Vivienne Westwood and with her trademark bird’s nest of brown curls piled up on top of her head, she’s the epitome of both the elegant and eccentric. Sitting with her in a boardroom at the Hotel Adlon in Berlin, I’m reminded of an observation her co-star in the 2002 film The Heart Of Me, Paul Bettany, once shared with me. “Barking mad, keen as mustard and funny as f***,” he said about the actress, and I’m inclined to agree.

Her most recent role as the late Queen Mother in The King’s Speech has endeared Helena to the world more than ever. Picking up four Oscars, seven BAFTAs and a Golden Globe during awards season last month, it’s perhaps the most successful film Helena has ever been in.

You sense that she’s partly sad and partly relieved that the marathon press run and awards season appearances for the film has now ended. Instead, she’s here to discuss a previous release, the BBC drama Toast which aired at Christmas and comes to DVD this week. Based on food writer Nigel Slater’s childhood memoirs, it sees Helena star as his wicked stepmother Mrs Potter, a chain-smoking Brummie who’s somehow charming, coarse, sympathetic and sexy, all at once.

You’ve just been through awards season with The King’s Speech. Are you looking forward to getting back to normality?

I’m really looking forward to it – it’s been very difficult. The Queen Mother said herself – and it’s good advice – “If you’re in the public eye, don’t complain, don’t explain and don’t ever speak publicly.”

Did the Oscars make you nervous?

Oh, yeah. You could make a complete tit of yourself, and if you do, there are a lot of people watching – so yes, things like that are nervewracking.

The King’s Speech has been so popular with audiences all over the world. Does it mean a lot to you to get fan mail?

It shouldn’t, because I just pretend to be other people for a living. Sometimes I go, “What am I doing with my life?” But then I get letters from young women, or people come up to me, and they say, “You’ve made such a difference to my confidence.” And that is a good thing. I should read more fan mail though. I’m crap at responding.

Do you think your dress sense has got more eccentric with age?

No! I don’t think so. It’s pretty difficult to self-assess. I’ve always been happy to wear things I like and not follow what’s in fashion.

What gave you that confidence?

I just thought I‘d never look good in what everybody else wore. So there’s no point trying. You just have to do what suits you, and it doesn’t matter if you don’t look like everybody else. Be you. That’s our gift and we’ve got to celebrate that, but it does take ages. I was wracked with self-doubt for years. I get spasms of it even now – I’m not indelibly self-confident.

Why did you make Toast?

Partly because I wanted to meet Nigel [Slater]. I went with my tape recorder to get all the info about Mrs Potter, and then at one point – which I was praying for – he said, “Do you want lunch?” It was really simple and so him; a mozzarella di bufala with a pesto dressing and beefsteak tomatoes. That was it. But it was fantastic.

Do you love to eat?

I love food. Elizabeth Taylor once said you have to choose between the body and the face at some point and I think she was right. I did diet when I was younger but now I just eat. I don’t overeat though. I’m rounder, but I think it does help the face. [Laughs.]

Who does the cooking at home?

I do. Tim definitely does not do the cooking! [Laughs.] I buy lots of cookery books, and I mean a lot. I’ll often go to sleep with one but I won’t necessarily cook from it. I always plan to though – it’s a comfort thing.

What is your best dish?

I make mean roast chicken, which is not exactly a dish. I’m quite good at cooking a piece of meat with a lovely sauce. I love sauces. Tim, unfortunately, does not – he likes simple things. His perfect dish is pasta. A very simple caprese. That’s all. You just dump it on the pasta and he’s very happy.

What qualities attracted to you to the men the in your life?

Oh, Jesus! I’ve been so long with the one man, the rest of them…

What’s sexy about Tim?

Tim? He’s a genius so that helps, and he has a great sense of humour. I know it sounds so boring, but if somebody makes me laugh, they’re in.

Does Tim get jealous when you collaborate with other directors?

No, he’s not at all jealous! He encourages me and I encourage him to work with other actresses. I know the directors I work with are all intimidated by ‘the boyfriend’ – although he’s the least intimidating person ever.

Does he write parts just for you?

No, absolutely not. I never have a say – quite the reverse. It’s sort of: “Avoid her, avoid her,” and then at the last minute, it’s “Gee, are you interested?” It is predictable, and maybe it’s boring, but at the same time, there is a huge logistical thing in its favour. We do have two children and it doesn’t make any sense for me to go across the world while he’s shooting.

Do you find the way you and Tim are portrayed in the media amusing?

I said this to Nigel [Slater] – we were talking about people writing things about you, and I said, “The further they get away from the truth, I think that creates more of a protective shell. If you’re in the public eye, and you’re going to be written about, you have to let this other self go.” People will always write and think all sorts of things – be irritated by us, have affection for us, think we dress coolly or disastrously. It’s whatever.

Are you a confident person?

I’m more comfortable with myself than when I was younger. I hated myself then. Wait, I didn’t hate myself – that’s a strong word. But I was so diffident. I didn’t know how to act, for one. I had no confidence in that area or in myself at all, really. I had a big inner critic and still do. I just don’t listen to it so much.

Were you ever worried about being typecast at the start of your career?

I think I got a bit tired of dealing with it, that’s for sure. I only do a part if I want to do it, for my own reasons – if I feel excited or inspired by it.

Has acting helped you to become more self-assured?

No, I don’t think so. It doesn’t come from the acting, although being in steady work has helped me. You always want to feel like you belong professionally, but confidence is dependent on so many things. You need to feel like you contribute to your community. But I don’t think I was unusual in my lack of confidence for an 18 year old. I think that was totally normal.

What are your strongest memories of childhood and growing up?

I’ve got lots. I was lucky. My biggest privilege was having two good parents. Even if I was hard on myself, I know my parents believed in me 100% and were supportive of whatever I wanted to do.

Was it hard to imagine what it would’ve been like if you lost a parent when you were young, as was the case for Nigel Slater?

In a way my father did die – the father that I knew. He became chronically disabled when I was 13 through an operation [to remove a tumour] that went very badly wrong. So that loss of the father that could do things with me was huge.

How would you describe your parents?

They had a great sense of humour and were liberal in character so nothing was ever expected of us. Also, we were unusual because my dad wasn’t the patriarch of the family – my mum was the soul, as she points out. Her side is half-French, half-Spanish, so it wasn’t a tremendously British household. I’m a mongrel, that’s the irony. There’s this thing about english roses but I’m definitely the chop off my mother’s block. I don’t even look that British.

You lived with your parents during your 20s. Can you imagine your children doing the same?

No! I’d like them to stay forever. And I did tell Billy the night he was born that this was it, I was going to be his only woman!

You had your daughter, Nell, when you were 41. How has having a second child changed you?

Nellie is extraordinary. A massive character! She was born happy. She came out and we thought something was wrong, she was so laid-back. She’s made a huge impact on our lives and it’s great, we’re lucky. We’ve got a boy. We’ve got a girl. They’re both healthy and they’re both really funny.

And finally, is it true you’re friends with Samantha Cameron?

I’ve known her for a long time, before David was even an MP. I’ve seen them through really horrible times with Ivan [their first son, who suffered from Ohtahara syndrome and died in 2009, aged six], and then really good times and they are always themselves. He’s not changed since he’s become Prime Minister, at all.

Toast is out now on DVD, Momentum Pictures, £15.99

Words: Tom Mottram