The Tudor Oysterdate chronograph reference 7031, nicknamed “Monte Carlo” or “Home Plate”, was introduced around 1971 and is Tudor’s first chronograph. It has a stainless steel case of about 40 mm with screw-down pushers, an acrylic tachymeter bezel and a Rolex-style Oyster case back. It runs the manual-wind Valjoux 7734 with 17 jewels, and the grey and orange dial has sub-dials set in a shape that resembles a baseball home plate.

Both nicknames are collectors’ tags, not Tudor names. Phillips notes the reference was made for a short time before the 7149 replaced it with a Valjoux 234 movement, and Tudor’s own history pages confirm the sequence. The case, crown and bracelet come from Rolex, and some auction essays compare the case to the Daytona 6263.

Collectors treat the 7031 as an early cult chronograph with an unusual dial, well below the price of a Daytona, though auction results of tens of thousands of Swiss francs show how far it has risen. It is long out of production.