Designers and sisters Savannah Miller (left) and Sienna Miller during a rehearsal for their Twenty8Twelve spring/summer London Fashion Week show, at the Old Sorting Office in central London Stock Photo - Alamy

Sienna and Savannah Miller design catwalk show - The San Diego Union-Tribune

Sienna Miller: Twenty8Twelve at London Fashion Week!: Photo 2239912, Savannah Miller, Sienna Miller Photos

Sienna Miller: Twenty8Twelve at London Fashion Week!: Photo 2239912, Savannah Miller, Sienna Miller Photos

Sienna and savannah miller hi-res stock photography and images - Alamy

Sienna Miller: Twenty8Twelve at London Fashion Week!: Photo 2239912, Savannah Miller, Sienna Miller Photos

Sienna and Savannah Miller design catwalk show - The San Diego Union-Tribune

Sienna and Savannah Miller on Twenty8Twelve and sisters, British Vogue

Sienna Miller and Savannah Miller London Fashion Week Spring/Summer 2011 - Twenty8twelve Fashion Show-Backstage The Old Sorting Office London, England - 18.09.10 Stock Photo - Alamy

Sienna and Savannah Miller design catwalk show - The San Diego Union-Tribune

Sienna and Savannah Miller design catwalk show - The San Diego Union-Tribune

Sienna and Savannah Miller design catwalk show - The San Diego Union-Tribune

Sienna Miller (left) and sister Savannah Miller backstage after the Twenty8Twelve fashion show at Howick Place, London, during the London Fashion Week Stock Photo - Alamy

Celebrity sisters Sienna and Savannah Miller pose for their portrait at the launch of their fashion label's latest collection: Twenty8Twelve. London F Stock Photo - Alamy