The Must de Cartier Tank, launched in 1977, is a version of Cartier’s classic rectangular Tank in vermeil, which is gold-plated sterling silver, with a quartz movement. It kept the Tank’s proportions, with the brancard sides and a cabochon crown, and was sold in a few sizes, with a lacquered or tinted dial, on a leather strap.

The Must range was introduced by Cartier chief executive Alain-Dominique Perrin to bring the house to a wider audience, with vermeil and quartz that made a Cartier Tank affordable at a fraction of the gold price. It sold in large numbers and is credited with the rebuilding of Cartier’s watch business.

Collectors regard the Must Tank as an accessible way into vintage Cartier, with the Trinity and tortoise dial variations being the most sought after. The original Must line is no longer made, but Cartier has revived the name with the Tank Must, which is in the current collection.