The brand is expanding rapidly after teaming up with the former tennis pro Roger Federer to create shoes suitable for the Swiss star’s sport and a mix of fashion-led collaborations including with the luxury brand LOEWE, actor Zendaya and singers FKA twigs and Burna Boy. In China, sales have doubled year-on-year. Growth has been strong in the US and mainland Europe and this month On will open its fourth London store, in Kensington.