The inaugural Royal Oak model made its debut in 1972 at the Basel Fair following two years of meticulous development. Apparently designed in one night by Gérald Genta, this extraordinary watch elevated steel to a new status. It pioneered the concept of "casual chic," marking a pivotal moment in the history of Audemars Piguet and luxury watchmaking. Between 1972 and 1976, the Royal Oak 5402 was the only Royal Oak produced by Audemars Piguet, available in a single material and with a single dial. In just four years, this radical timepiece left an indelible impression on the industry before transitioning, from 1976 onwards, into one of the most extensive collections in horological history. The 5402ST remained in the catalogue for 15 years. 4288 units were sold, all being classified as part of the A, B, C or D series. This timepiece features the original blue dial, which has acquired a superb purple grey tint over time. The case and bracelet are in steel and have been preserved in beautiful condition. More importantly for such a collector's item, the watch is entirely original, meaning that no parts have been changed. This timepiece is not only a masterpiece of design, but has become an icon in the world of watchmaking.