The Citizen Tsuno Chrono brings 1970s bullhead design to a modern driver’s watch

Until this year the long, hot summer of 1976 was widely considered to be the, er, longest and hottest in Britain ’since records began’ – making it the ideal moment (over here, at least) for Citizen to unveil the precursor to its revolutionary Eco-Drive solar-powered technology.

Global warming, rising temperatures and the wilting planet may be front and centre today, but the Japanese watchmaker was already trying to do something about it 50 years ago when it launched its ‘power for life’ system to counter the rapidly increasing number of quartz watch batteries being sent to landfill.

Citizen’s original Crystron Solar Cell watches featured silicon cells atop their dials which powered the movement by absorbing sunlight but, although it worked well, a couple of days’ autonomy was all a wearer could expect.

A decade later an improved cell design and better electric capacitors enabled the system to work using both the sun and artificial light, and extended the power reserve to more than a week – but it was the launch of Eco-Drive in 1995 that truly established the technology’s long-term viability.

Eco-Drive combined translucent dials hiding solar cells that transformed sunlight into energy to power tiny, lithium batteries which quickly charged to provide sufficient electricity to run the movement for at least six months – even when the watch was left in the dark. Soon, Citizen combined Eco-Drive with radio-controlled timing and, more recently, GPS and smart connectivity to create watches that can theoretically run forever and are also ultra-accurate.

To mark 50 years since it first set out to tell the time by harnessing the power of the sun, Citizen has released a new 5000-piece limited edition driver’s watch called the Tsuno Chrono which harks back to the ‘bullhead’ designs of the 1970s.

Bullhead chronographs are so called because they combine an ovoid case shape with top-mounted crowns and chronograph push-pieces (although the Tsuno does have another crown at the five o’clock position, which is used to set and control its alarm function).

In addition to being able to wake you up in the morning, the watch incorporates a flyback chronograph, 12-hour totaliser, date display, tachymeter scale and power reserve indicator – all of which are arranged around a motoring-inspired British Racing Green dial with racy orange highlights.

With so much going on, the Tsuno is inevitably on the large side (its two-tone case measures 44mm in diameter and 15.25mm thick), but that does help with legibility while at the wheel.

And if affordable, statement-making, multi-function, planet-friendly watches are your thing, it’s difficult to think of one that trumps it.

Citizen Promaster Tsuno Bullhead Racing Chrono 50th Anniversary, £895. citizenwatch.co.uk