You didn’t need to be Sherlock Holmes to deduce that the Rolex Explorer line was due a refresh, and indeed it came to pass. The big news from the brand at this year’s Watches & Wonders trade show was a subtle redesign and movement upgrade for the speleologists’ favourite, the Explorer II (£6,800), with its orange second hand and white face. More radical was the work on the Explorer I (£8,700), including a reduction in diameter from 39mm back to a more historic 36mm and availability in Rolesor (steel and gold).

While Rolex fans were excited by a new model of one its classics, Patek Philippe watchers were similarly obsessed by the final series of the current generation of the much-loved Nautilus. After the global outcry that greeted the shock discontinuation of the Ref 5711 (and saw already stratospheric pricing on the secondary market leap even higher), a fortunate few will have the opportunity to buy a special green-dial version of what, over the past few years, has become one of the world’s hottest watches (from £26,870).

Swollen by an influx of big names from the old Basel watch fair, including Rolex, Patek Philippe, Chopard and Chanel, the Geneva-based Watches & Wonders Fair is now in its second year as a digital exhibition. But this time, there is a real-life, real-time show with actual physical real watches directly afterwards in China; a market doubly important now that domestic buying has been boosted by onshoring of what, in pre-pandemic days, would have been travel spending in Europe.

As analogue – almost infinitely repairable – objects, traditional timepieces have good sustainability credentials, but it is always possible to do more, and to judge from the actions big and small being taken, it’s an area brands believe to be of concern to the all-important millennial. Panerai is bruiting about its concept Submersible eLAB-ID as “the watch with the highest percentage of recycled-based material ever made”, positioning the brand “to lead a movement toward more environmentally responsible watch manufacture”. Moreover, CEO Jean-Marc Pontroué has listed his suppliers, throwing down an open-source eco-gauntlet. Brands are discovering plenty of scope for innovation: for instance, Panerai favours straps of recycled plastic made by Morellato, while IWC launches a new range of leather-free, paper-based TimberTex watch straps. Even battery-powered watches are getting an environmental upgrade with a solar-powered Tank chez Cartier (£2,390).

Watches & Wonders is not the place to drill down into individual models in detail, but rather an opportunity to try to get a panoramic view of the landscape. And a quick glance across brands shows that vintage still seems strong: neither Breitling nor Omega are Watches & Wonders exhibitors but the former’s Premier range majors on nostalgia while the latter’s recently relaunched Seamaster incorporates vintage styling cues. Elsewhere, Jaeger-LeCoultre has seen a new generation become interested in its deco classic the Reverso, which turns 90 this year.

But the biggest (v)indicator of the power of the past is the recent resurgence of Cartier as a watchmaker, under the leadership of Cyrille Vigneron. This year sees the reappearance of a 1970s icon, the Tank Must, which first appeared as a diffusion range over 40 years ago. One of the characteristics of the old Must was the use of colourful dials and, coming after last year’s super-successful Rolex Oyster Perpetual with coloured dials, the return of the Must with green, claret and blue faces seems timed to perfection (£2,490).

Of course, Cartier has been helped by a broader return to smaller watches and this industry-wide shift is noticeable this year, even at brands which did so much to establish the big-watch trend of the early 21st century. Panerai has come up with a 38mm diameter Luminor Piccolo Due (£14,700), and even the 46.2mm IWC Big Pilot is now also available as the slightly smaller Big Pilot with a 43mm-diameter case (from £7,200). Meanwhile, their Richemont stablemate A Lange & Söhne, the connoisseur brand from Saxony, has reintroduced a reduced-diameter version of its Flagship Lange 1, the Little Lange 1 (from £38,400), which first appeared in the 1990s when it was made for the then-powerful Japanese market. Now the Little Lange 1 is seeking – and in my view deserves – success around the world. But hardcore Lange lovers need not worry that the brand has abandoned its chunky complicated heartlands: a second series of its cult Triple Split (£152,100) has also been announced.

Thin is also in. One of the biggest promulgators of size-zero watchmaking is Bulgari, which, finding it has a hit on its hands with the Octo Finissimo line, each year presents a new world record in slimness (although sometimes records I did not even know needed breaking) to showcase its growing expertise in movement miniaturisation. This year’s record breaker is a super-skinny titanium-cased perpetual calendar with retrograde indices (£49,000): a handsome addition to an increasingly impressive model range.

In watches as in life, a little weight loss can have dramatic results: take this year’s ultra-slim skeletonised Piaget Polo (£26,500). It is no secret that I was not a fan when the steel sports watch launched a few years ago – to my eyes it looked like it was trying to be a Nautilus and the bracelet lacked finesse – but with the ultra-slim skeleton version the transformation is little short of miraculous. The brand’s generations of expertise in slim movements are distilled into a movement I could watch all day and the slimmed-down, less prominent bezel moves it away from comparisons with other well-known watches. The bracelet still lacks finesse (IMHO) but once you make use of the quick strap-change mechanism and substitute the leather band you are unlikely to want to take it off.

Skeletonising used to be a dress-watch-only refinement but technological advances and demand from younger clientele has seen a rise in high-end watchmaking in a sporty case. Vacheron Constantin launches a skeleton version of its Overseas ultra-slim perpetual calendar (£122,000); while Kering’s Ulysse Nardin introduces a high-tech looking skeletonised version of its diver (£18,050).

Indeed this year sees developments across several well-known and robust sports pieces. “We wanted to make the Defy design even more futuristic and assertive,” says an unapologetic Sébastien Gobert, designer at Zenith, who describes the brand’s titanium cased Defy Extreme (from £15,300), as “faceted and carved like a boulder in a storm”.

Titanium was the metal chosen by George Bamford for a much-lauded collaboration with TAG Heuer on its Aquaracer. Now TAG Heuer has come up with a new steel version (£2,500) of its popular underwater workhorse, instantly recognisable thanks to the dodecagonal bezel. Indeed, dive watches are surfacing right across the spectrum, from luxury goods house Louis Vuitton, which issues the Tambour Street Diver, to renascent Rolex diffusion brand Tudor. The latter has built its revival in great part on its classic Diver the Black Bay Fifty-Eight. This year sees two highly attractive new 39mm variations: an 18ct gold, green dial and bezel iteration (£12,610; there has not been an 18ct Tudor for years) and an extremely pleasing silver version with taupe dial (£3,320).

Having handled the silver pre-launch I can testify to its charm, but alas I have yet to see the gold version in the metal: even though the experiences of the last 12 months teach that contemporary tech is going to continue to play an important role in the centuries-old business of making mechanical watches, there is no substitute for having the watch in the hand and on the wrist.

Click here for more FT coverage of Watches & Wonders 2021