Little Mix look stunning in their 70s inspired outfits at the #CapitalSTB This image appears in the gallery:Little Mix And Fifth Harmony Lead The Summertime Ball Red Carpet Arrivals 3. Little Mix look stunning in their 70s inspired outfits at the #CapitalSTB Picture: PA 23 images See the full gallery: Little Mix And Fifth Harmony Lead The Summertime Ball Red Carpet Arrivals