Monochrome Watches
An online magazine dedicated to fine watches

MB&F Legacy Machine Perpetual, now in Yellow Gold

Possibly the most technologically advanced QP on the market revealing its mechanism dial side, now in a stunning yellow gold case.

| By Rebecca Doulton | 4 min read |
MB&F Legacy Machine Perpetual Yellow Gold

Developed with watchmaker Stephen McDonnell in 2015, the astonishing Legacy Machine Perpetual turned conventional perpetual calendar movements upside down and inside out. Reinventing the QP complication from scratch, with a default 28-day month and a “mechanical processor”, McDonnell’s novel technology eliminates the drawbacks and fragility of conventional QPs and impressed the jury of the GPHG to take home the Best Calendar Watch award of 2016. Since its launch, the LM Perpetual has appeared in red gold, platinum, white gold and titanium. Today, as January 2020 draws to its close, it’s time to unveil a spectacular 18k yellow gold model limited to 25 pieces.

Unconventional thinking

The birth of the first Legacy Machine in 2011 was a rara avis in MB&F’s universe of intergalactic spacecraft with astonishing cases and complex displays. The Legacy Machine responded to Maximilian Büsser’s vision of producing a watch that he could have created had he been born in 1867. With its steampunk personality that Jules Verne would have warmed to, the salient features of the LM were the large balance wheel placed smack in the centre of the dial and the pronounced domed sapphire crystal over the dial.

MB&F Legacy Machine Perpetual Yellow Gold

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Rethinking the QP complication from scratch

Four years later, in 2015, the Legacy Machine Perpetual was unveiled, the brand’s first perpetual calendar complication made in collaboration with Stephen McDonnell. An independent watchmaker from Northern Ireland, McDonnell had been mulling with an idea to redesign the complication and eliminate many of the drawbacks associated with the 150-year-old technology still used today on conventional QPs.

MB&F Legacy Machine Perpetual Yellow Gold

The calendar indications of most perpetual calendars are synchronised by a long lever (grand levier), which in turn requires a great deal of space to perform its backwards and forwards motions. This traditional system also assumes that months have 31 days. To adjust for months with fewer days, the long lever skips over superfluous dates to reach the first day of the new month. However, any manipulation or adjustment of the date during this changeover period can damage the mechanism.

MB&F Legacy Machine Perpetual Yellow Gold

McDonnell’s dream was to create a less fragile mechanism that would be practically “foolproof” allowing the correctors to be pressed at any time of day. As McDonnell explained, “with conventional systems you are always obliged to move through 31 days, even if you don’t use 31 days. I wanted to create a mechanism that will jump precisely from last day of the month (be that 28, 29, 30 or 31 days) to the first with no hesitation.” The solution was a mechanical processor composed of a series of superimposed discs on a planetary cam. Taking the default number of days in the month at 28 and adding the extra days as required, McDonnell’s invention meant there was no skipping over redundant days and no chance of the date jumping incorrectly.

Nothing hidden

The 18k yellow gold case measures 44mm with a height of 17.5mm and features refined contrasting brushed and polished finishes. The spectacular domed sapphire crystal reveals the fascinating architecture of the movement on the dial rising from the dark blue base and supported by pillars.

MB&F Legacy Machine Perpetual Yellow Gold

In pride of place, the 14mm balance wheel floats above the centre of the dial and is surrounded by four suspended dials to relay the information of the perpetual calendar mechanism and the time.  The dials corresponding to the date, day and month are hollowed out in the centre to reveal more elements of the 581-part movement and all the hands are blued. In addition to the beautiful 3-dimensional architecture of the dial, the beauty of this movement is that all the functions – hours, minutes, day, date, month and retrograde leap year – can be adjusted independently by pressing the correctors on the caseband.

MB&F Legacy Machine Perpetual Yellow Gold

The reverse side of the case reveals other parts of Stephen McDonnell’s fully integrated, manual-winding perpetual calendar movement with its mechanical processor and inbuilt safety mechanism. The escapement is clearly visible as are the double barrels providing the movement with 72 hours of autonomy. In keeping with its 19th-century spirit, the hand-finishes are superlative with internal bevelled and polished angles, large gold chatons, Geneva waves on the bridges and hand-engraved surfaces.

MB&F Legacy Machine Perpetual Yellow Gold

Availability and price

The new MB&F Legacy Machine Perpetual Yellow Gold comes with a navy blue alligator strap with a yellow gold folding buckle. It is limited to just 25 pieces, which are now available from retailers, and will retail for CHF 158,000 / USD 167,000 / EUR 147,000 (excl. tax). More information at

5 responses

  1. Gorgeous.
    Truly Innovative.
    And an MB&F, to boot!

    The first PC that I have been tempted to buy. Just a shame that my bank manager is such a nay-sayer.

  2. p.s. As Nicholas Parsons, that great fan (and man) of horology, might have said, a watch without repetition, deviation or hesitation.

  3. Like its concepts and innovations, but it’s way too huge for a perpetual calendar watch.

  4. I don’t normally care for anything as fussy as this but it is beautifully finished, more to be looked at than worn. These days it is so refreshing that someone will look at something and improve it radically by just looking at the problem from a slightly different perspective.

  5. Unfortunately 44mm is too big for me and the 147 exc tax as well. Apart from that I would absolutely love one

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