In London, The youngest in the Cartier brothers, Jacques, opened his boutique and ultimately moved it to its present-day site at 175-177 New Bond Avenue. Jean-Jacques was enamoured with watches, and he tirelessly designed and re-made the Tank in attempts to maintain it appropriate for his progressively hip Londoner clientele, https://www.watchesworld.com/a-history-of-watch-reference-numbers/