Thanks to IWC’s celebration last year of this hallowed timepiece, IWC’s Mk11 – the only “Mk” denoted by Arabic numerals – is once again a hot property. It’s been a collectable for at least 35 years, from the dawn of the mechanical watch revival and the explosion in interest in military watches. There are several reasons for this, the most obvious is that it is one of those pieces, like the original Patek Philippe Calatrava and the Rolex Explorer, which is so close to perfect that its creators have been stumped for decades trying to improve upon them.

This masterpiece arrived just after the end of the Second World War, a replacement for the Mk X of “Dirty Dozen” fame. The Mk 11, unlike the Mk X, however, was designed for pilots, not infantry or ground troops, so it was conceived to deal with the requirements of a navigator’s timepiece, which IWC upgraded for the era of radar-equipped cockpits.

The IWC “Dirty Dozen” watch, 1940s

Its specification thus includes superlative legibility thanks to a 3-6-9 dial with triangle at 12 o’clock, incabloc shock protection, sweep-seconds hand in place of a sub-dial, full protection against magnetism, hacking seconds for watch synchronization and a rugged 36mm steel case. Inside is what one many regard as one of the finest manually wound movements ever created: genius watchmaker Albert Pellaton’s magnificent Calibre 89.

IWC Mk 11

Originally delivered in 1948 for the RAF, their Mk 11s had casebacks engraved with a combination of numbers and letters, plus individual serial numbers: 6B/346. The “6B” showed the watch as “Aircraft Navigation Equipment, Accessories and Unit Servicing Parts”. The “346” was the result of chronological numbering. Each wore the Ministry of Defence’s “broad arrow” on its dial, though other air forces were issued Mk 11s – thus much rarer and collectable – and many reached civilians. It stayed in production into the 1980s.

IWC Mk 11

The Mk 11 happens to be one of the first vintage watches I ever purchased, some 30 years ago, for the then-considerable sum of £250 – roughly £575 in today’s money. Guess I did well: today you’d be lucky to find a VG+ Mk11 for under £4,000.