Ben Francis, 27, started this fitness clothing brand in his parents’ garage in 2012. It has since gone global under chief executive Steve Hewitt, 46, with its clothing and accessories now sold directly to consumers in 178 countries via 13 multilingual websites. By sponsoring popular YouTube and Instagram ambassadors to showcase its products, Gymshark has attracted a combined social media following of 116.5m sports and fashion enthusiasts. Last year, international sales reached £143.5m and it opened a new American headquarters in Denver.