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 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

Savannah and Sienna Miller London Fashion Week Spring/Summer 2011 - Twenty8Twelve - Backstage London, England - 18.09.10 Stock Photo - Alamy

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

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

Twenty8Twelve by s. miller Takes London Fashion Week

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

Nervous Sienna Miller makes London Fashion Week debut as her THREE mums turn up for support

Sisters Savannah and Sienna Miller lend style to high street brands, Fashion

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