DESCRIBE WHAT YOU'RE WEARINGThe black dress is by Roland Mouret, the shoes by Miu Miu and the Panther bag and ring by Cartier.
DO YOU ALWAYS DRESS LIKE THIS IN PUBLICITY SHOTS?I am beginning to get more experimental and that is a confidence thing. The problem about being an actress is that often you can look quite homogenous and if you make a mistake, you make it publicly. I have discovered what really suits me.
SO HOW DO YOU DESCRIBE YOUR STYLE?A mad mother with two children (aged five and three) and a dog – eclectic! I am always conscious of trying to look co-ordinated, but if I can get away with it, it's just jeans and anything that can take vomit or spilled food.
ARE YOU A SHOPPER?Oh, yes, but more for antiques and bedspreads – at the moment I am interested in shabby chic. I like a rustic feel in the house. I am a bit of a magpie and am very careful when it comes to clothes. I never leave it too late to buy winter clothes.
FAVOURITE SHOPS? Liberty in London, because it has everything and is architecturally so beautiful. I like Alfies Antique Market in Marylebone, and Islington has fantastic vintage clothing stores. Internet sites I like are net-a-porter, Browns and Matches, but I think net-a-porter has the edge.
SO YOU'RE NOT A HIGH STREET FAN? I get very angry with high street shopping. I don't like how cheaply things are made. When I buy I want things to last for at least two years. You have to think like the French, about cut and fit, and if something doesn't look right, don't buy it.
WERE YOU ALWAYS INTERESTED IN FASHION? Not remotely. I didn't grow up with it – there was a certain attitude to it, but now I see that it has to be celebrated and I love the power it gives women. I really believe that women dress for women.
WHAT DO YOUR CLOTHES SAY ABOUT YOU? I don't know really. I hope that they flatter me and that they are not too loud or confrontational. I want to feel comfortable and have a bit of an edge. I think Róisín Murphy (the singer) is fantastic and I love her style.
DO YOU LOOK FOR SPECIFIC THINGS WHEN YOU'RE BUYING? Not really. I try to go with what is on-trend, but only if it suits me. I am quite short at 5ft 3in, so I need clothes that elongate me.
FAVOURITE DESIGNERS? I love Chanel, Balenciaga and Chloe and Stella McCartney, particularly her ethical stand, which is very brave in the fashion industry. I found Todd Lynn's latest show, which was covered in furs, utterly disgusting.
INTERESTED IN BAGS? I am terrible about bags. My husband goes bananas. I am the person who hides things in the back of wardrobes. I am passionate about Mulberry, Cartier and Chanel bags.
WHAT ABOUT SHOES? I get very annoyed about shoes. During the filming of Material Girl (her TV new series) I wore shoes by by Galliano, Louboutin and Prada. Nothing fitted and they were so uncomfortable my muscles went into spasm. If I spend €400 or €500 on shoes, I expect more. I'm sorry, I am trailer trash – I like trainers; but I do also love Jimmy Choos.
THE MOST YOU'VE EVER SPENT? About €4,000 on a black Balenciaga dress – but when you think about how much couture costs . . . I probably didn't shop for a year after that. I am hoping to hand it down to my daughter some day.
HAS THE NEW SERIES ALTERED YOUR VIEW OF FASHION? Yes, it has overhauled my whole idea of the industry – I had to visit all sorts of people for it. In my head you sat down and drew a picture and that was how designers worked. But it's all about what is current at the time, about undercurrents, and it is so creative I fell in love with it.
Dervla Kirwan plays the role of Davina Bailey, an eccentric megalomaniac fashion designer, in the forthcoming six-part series Material Girl to be shown on BBC1 in September
DERVLA KIRWAN, actor