CRANS-MONTANA – There is a particular kind of confession that slips out when a watchmaker forgets he is being interviewed.

High above the clouds at Chetzeron, the picturesque mountain hotel in the Swiss ski resort of Crans-Montana, Zenith chief operating officer Romain Marietta admits something mildly heretical for a man who has spent 20 years obsessing over mechanical precision.

Tiny date windows, he says with a laugh, are becoming harder to read.

“Once you get past 30, it becomes a bit less easy to see,” the 44-year-old says, joking that he may soon have to start looking at watches with bigger date displays.

It is an amusing admission, not least because one of the four versions of the watch he is here to unveil to a group of international journalists does away with the date window altogether.

The moment sets the tone for a conversation that is less about specifications than restraint, honesty and the challenge of persuading people to buy something nobody strictly needs.

For Zenith, that challenge invariably begins with the El Primero.

Unveiled in January 1969, it was the world’s first automatic, fully integrated high-frequency chronograph movement, beating at a then-blistering 36,000 vibrations an hour, or 5 Hz. It almost disappeared during the quartz crisis of the 1970s, surviving only because Zenith watchmaker Charles Vermot defied orders to destroy the machinery needed to make it and secretly hid the tooling in the manufacture’s attic.

More than half a century later, that engineering legacy powers Zenith’s new Chronomaster Solo Sport. Except this time, the brand has done something that sounds almost sacrilegious: it has removed the chronograph.

Gone are the pushers and chronograph sub-dials. Inside the 40mm steel case instead sits the El Primero 3620, a three-hand movement derived from the calibre 3600. It still beats at the El Primero’s signature 5 Hz frequency and comes with a silicon escapement, star-shaped rotor and 60-hour power reserve.