Sienna and Savannah Miller's sample sizes

Sienna and Savannah Miller always get a sample of their designs made in both their sizes so they can make changes.

The sisters' brand Twenty8Twelve is now in its 11th season and Sienna says the only way they know if the clothes are right is to try them on.

She said: "We now get each sample in both our sizes which has made a huge difference to the way we make changes. I've had the great fortune to wear a lot of beautiful designer clothes, and you know when something feels right.

"We've also moved all our tailoring to London as well which has made a massive difference in terms of quality and fit - and working with a pattern cutter here feels right for the brand too."

While Savannah feels the pair may have been too edgy with their designs in the past, she now thinks they have finally hit on the perfect style for the label.

She told vogue.co.uk: "I feel like we've been finding our niche. Maybe we've tried to be a bit too avant garde in the past, but now we do that with print and texture and just focus on making wearable clothes we'd love to wear. We have an amazing team of seven unsung heroes who work with us - they really understand us and where we want the brand to be - and we're getting there."