Although the jewellery firm Cartier is credited with producing the first wristwatch, many of the innovations in watch technology that are now taken for granted by most people were the work of rival company Rolex. Among these are the invention of a synthetic cover for the watch face that would prove far tougher than the traditional glass, a self-winding mechanism that enables a watch to keep going simply from the movements of the wearer's body, and the first waterproof wristwatch.

The company that we now know by that name was originally founded under the name Wilsdorf & Davies. Hans Wilsdorf, who was born in Kulmbach, Germany, in 1881, was just 24 when he set up in business in 1905, yet by 1910 one of his products was awarded Official Chronometer Certification by the Bureau Officiel in Switzerland. It was the first time this prestigious official recognition had been awarded to a wristwatch. Four years later the Kew Observatory presented Rolex with a Class A Precision award following a series of gruelling tests which included baking the watch in an oven and chilling it in a refrigerator.

In 1926 Rolex created the innovative Oyster watch. Its name is said to have originated at a dinner party hosted by Hans Wilsdorf at which a guest complained about the trouble he was having opening an oyster. Wilsdorf remarked that he hoped that the design of his latest watch would make it every bit as challenging to break open.

The Rolex Oyster was designed to offer precision time keeping even under the most adverse conditions. The watch was to be put to the test in dramatic circumstances.

On October 7, 1927, the London typist Mercedes Gleitze swam the English Channel. She completed the swim in just over 15 hours, and was so exhausted upon reaching the English coast that she collapsed and was unconscious for nearly two hours.

Four days later another woman, Mona McLennan, claimed to have swum the Channel in just over 13 hours. The success of another attempt just days after Gleitze had completed her crossing raised suspicions, and eventually McLennan confessed that her swim had been a hoax. In the light of this suspicion was also cast on the truth of Gleitze's Channel crossing, but the indignant typist silenced sceptics by vowing to repeat the swim.

The date of October 21 was set for the attempt and this time public interest was phenomenal. It was in this context that Wilsdorf decided to sponsor Gleitze by giving her an Oyster wrist watch on the condition that she wear it during her swim and then provide a written testimonial as to its performance.

Unfortunately Gleitze did not complete the Channel crossing on this occasion, and had to be rescued seven miles short of her goal. However, the endurance she had shown during the crossing - undertaken in the inclement weather conditions inevitable so late in the year - persuaded her critics that her earlier attempt had been as successful as she claimed.

And Gleitze did provide a testimonial to the effectiveness of the Rolex Oyster watch. She had worn it from a pendant round her neck during the swim, and it prove to have kept good time throughout. She wrote to Wilsdorf: 'You will like to hear that the Rolex Oyster watch I carried on my Channel swim proved itself a reliable and accurate timekeeping companion even though it was subjected to complete immersion for hours in sea water at a temp of not more than 58 and often as low as 51. This is to say nothing about the sustained buffeting it must have received. Not even the quick change to the high temp of the boat cabin when I was lifted from the water seemed to affect the even tenor of its movement. The newspaper man was astonished and I, of course, am delighted with it.'