The story of Rolex is intimately associated with human achievement. Hans Wilsdorf, the company’s founder, saw the mutual benefit of equipping people who were record breakers with an Oyster watch: the first of a long line of athletes and explorers was Mercedes Gleitze, the first British woman to swim the English Channel.

In 1927, a young British secretary called Mercedes Gleitze took a place in the annals of watchmaking history with a sporting exploit that brought the first waterproof watch to the world’s attention. The 26 year-old swam the English Channel wearing a Rolex Oyster, spending more than 10 hours in the chilly waters between France and Great Britain. At the end of the swim, the waterproof wristwatch was declared to be in perfect working order.

She was the first Englishwoman to manage the arduous swim, still a rare feat at the time, and she earned huge popular acclaim. Rolex’s founder and director, Hans Wilsdorf, celebrated the landmark event with a full-page advertisement on the front of London’s Daily Mail proclaiming the success of the first waterproof wristwatch and chronicling 'the debut of the Rolex Oyster and its triumphant march worldwide'. Mercedes Gleitze effectively became the first Rolex Testimonee, a symbol of achievement who also demonstrated the new watch’s qualities in action.

It was a turning point. Although the wristwatch is taken for granted nowadays, a century ago pocket watches were the norm. The practical timepiece championed by Rolex owes much of its success to the painstaking development of waterproofing.