When it comes to military watches, the so-called Dirty Dozen is the holy grail for collectors. These are the first 12 wristwatches specifically designed for British Army service. They were commissioned during the second world war by the Ministry of Defence and known at the time as the W.W.W.s – Waterproof Wrist Watches. Delivered in 1945, most remained in service until the 1960s.

The manufacturers selected were Buren, Cyma, Eterna, Grana, Jaeger Le-Coultre, Lemania, Longines, IWC, Omega, Record, Timor and Vertex.

It’s the last one we're particularly interested in – the only British brand in the line-up. During the 1920s and 1930s, Vertex was the biggest watch manufacturer in Britain, with factories in Switzerland, too. Before the MoD wristwatch, it was making the chronological instruments for the Hurricane and the Lancaster bomber.

But after the end of the war, the business became unsustainable. The brand lay dormant until last year, when Don Cochrane – the great-grandson of the company’s founder Claude Lyons – resurrected it.

He relaunched it with the superb M100, a military cap doff to the original 1944 Cal59. It was a very cool watch, but there was a slight issue – only 600 were made and you had to be invited to buy one. This was a clever ploy – firstly, because it created an air of mystique about the brand; and secondly, because it limited the speed at which they needed to be made. The company is still a fledgling, despite its storied past, so Cochrane was keen it didn’t grow too big too fast.

The good news is, you don’t have to be invited to buy this one. The bad news is only 150 are being made

Buoyed by the success of the M100, Vertex launched the M100B earlier this year. And the good news is, you don’t have to be invited to buy this one. The bad news is only 150 are being made, so you will have to get in there quick.

The ‘B’ refers to black – as the new version comes in Diamond Like Carbon. Cochrane explains this is more than just an aesthetic choice: “I would like to think that, had the technology been available, the original W.W.W Cal59 would have been made to be non-reflective. Creating the M100B has allowed us show just how perfect that would have been.”

The M100B is packaged in a hard-as-nails Peli case and comes with three straps – a black rubber two-piece and two nylon NATO-style straps in black and red, both with black DLC hardware. The innards of the watch are unchanged: a custom ETA 7001 handwound movement with a 42-hour power reserve.

The brief for the original Dirty Dozen manufacturers was to build a highly durable, reliable, and legible watch. The new Vertex M100B certainly manages this – and then some.

£2,625, vertexblack.com