Tudor, Rolex's sportier (and more affordable) sister brand, introduced the Oysterdate chronograph in 1970. The ref. 7031 and 7032 featured a 40mm Oyster case and a Bakelite tachymeter on the 7031, and a stainless steel tachymeter bezel on the 7032. Both the dial of the ref. 7031 and ref. 7032 sported a striking color scheme in orange, black, white, and matte grey. 

In 1971 Tudor improved upon the design of the previous chronographs with the ref. 7159, and debuted it at Baselworld. The stainless steel case remained, equipped with screw-down winding crown and chronograph pushers. However, the dial now bore a chapter ring of 45-minute and running seconds, giving it the look of a roulette table--hence the nickname "Monte Carlo." Also improved was the movement, changed from the reliable Valjoux 7734 to the more refined Valjoux 234 with a column wheel.