Last year at Watches&Wonders Vacheron Constantin took the covers off the Maître Cabinotier Astronomica, a multi-million dollar wristwatch with 15 complications. Now at Watches&Wonders 2015 (which also happens to be the stage to showcase the most complicated watch ever) Vacheron Constantin has once again revealed a unique creation, the Maître Cabinotier Perpetual Calendar Regulator that combines a regulator-style time display with a concisely laid out perpetual calendar.

The latest addition to the Maître Cabinotier collection of unique timepieces, the Perpetual Calendar Regulator tells the time like an antique precision clock, with the hours and minutes on separate sub-dials for better legiblity. Known as regulator clocks, such clocks were usually the reference for other timepieces in places where precision timekeeping mattered, like watch factories an observatories.

Here the hours are located at 12 o’clock and the minutes on the central axis (though traditional regulator clocks had the hours at six o’clock). And the perpetual calendar is integrated in a similarly legible manner, with the day and month shown in windows on either side of the hours, while the date and moon phase at at six o’clock. A tiny round aperture at the four o’clock marker on the hour sub-dial show the leap year.

Though the layout is simple, the dial is decorative. A glossy brown, the dial is finished with a swirling, complex guilloche. The hands are spade-shaped while the hour markers are tiny pyramids. To match the colour of the case, the hour markers, hands, window frames for the month and day, as well as the moon and star, are all in pink gold.

The 42mm pink gold case contains the calibre 2460 RQP (short for régulateur quantième perpétuel), an automatic movement with a 40 hour power reserve. While the mechanism for the regulator time display and perpetual calendar were developed for this specific watch, the base movement is the same top-of-the-line calibre found in several other watches, including the Harmony Dual Time. The Maître Cabinotier Perpetual Calendar Regulator is delivered with a watch winder, stylus to set the calendar as well as a magnifying glass.