"That's the wonders of modern technology. We Skype a lot," Sienna says. "There are such great vintage stores and fabric places here that I can source and send my ideas back to Savs and vice-versa."
On Monday--Sienna's only night off--the Miller sisters spoke with WWD about what's next for the British label.
WWD: Sienna, you just moved to New York temporarily and Savannah, you're visiting here for the week. How are you finding the city so far?
Sienna Miller: I love New York. I was born here so I feel like I have an affinity with the place. But I'm here just for four months doing the play.
Savannah Miller: I love the pace here. London's great but it's a sleepy town compared to New York. This is on a completely different level. The energy is so exciting and it's impossible not to get caught up in that.
WWD:Sienna, you have a pretty grueling schedule with the play. How are you balancing social life and working?
Sienna: Yeah, this is my one night off. It's grueling but it's the best kind of grueling. It's a marathon. [But] it's what I love doing so really it's exciting to go to work everyday doing a play on Broadway. I just look at 42nd Street and I can't kind of believe I'm there doing it.
WWD: What's it like working with each other on the collection? Do you always get along?
Savannah: It's so great. We never fight. We really make an effort to see everything from the other's point of view and as a result the product is much clearer.
Sienna: We've never had a fight about work. We totally respect each other's aesthetic. They're really different so the combination of the two really works for the label.
WWD:You worked a lot with denim for spring. What's your definition of the perfect jean?
Sienna: Personally, I like thin denim. I don't want something that's bulky. [And] I like a bit of stretch in there. It was really hard thing to get the denim right. I find with jeans, it's a question of like a millimeter. It's really got to fit you in that right place. Spring/summer was really the first time we nailed our denim.
Savannah: The jeans that we've developed have the four-way stretch. It's a really amazing technology by which the denim stretches completely around your leg so you feel like your leg's molded into the jean. They're like a dream.
WWD:So what's the timeline in terms of Fall 2010?
Savannah: All done. All designed, all fitted, all fabrics approved. We've started making our samples now. It's crazy that it's so far in advance.
WWD:So what can we expect to see?
Sienna: Certainly with spring-summer, we brought it out a little bit more. I think we played it a bit safe before and we're trying to be much more adventurous now. I think we're going to have a lot more color and more crazy prints.
Savannah: It's gone on a bit of a wild woman feel.