Originally Posted by
M4tt
Sorry, I just realised that no one has actually answered the OP questions.
So here we go:
That's a 6b/159 and the reason is to do with accuracy. The Omega 30SCT2 movement inside it was regulated poised and balanced to a chronometer standard (but not formally certified) and over 10 ligne, even though it doesn't have fine regulation. As such, it would have been specifically a navigators watch (during the early years of the war), while a 6b/234 would have been a pilot's watch as it would have a minimum of an 8.5 ligne non chronometer movement and would have been cheaper all round.
Later in the war, post the Butt report and the realisation that the majority of navigators simply were not up to the job and the expansion of Bomber command, the 6b/159 pattern watches became reserved for the very best navigators, usually found in either five group under Don Bennett (who had an obsession with navigation) or the Pathfinder Force (PFF) and PFF and five group watches too the regulation,checking and servicing of watches very seriously as good timekeeping is the basis of good navigation.
From that point onwards, only the finest navigators (and sometimes pilots) in special operation squadrons such as 617 (itself in five group) and the PFF would get (usually Swiss) 6b/159 while the rump would get 6b/234 (usually American) From companies like Elgin and Waltham (care with these as they are usually highly radioactive having used radium in the lume). The earlier 6b/234 were usually the same standard as ATP and you'll sometimes find a Bravington for example with a 234 marking from early in the war - obviously these are quite rare as the force was much smaller and the losses shocking. They are still dirt cheap.
The idea was that the precision navigation was undertaken by the PFF or five group (supported by other navigation aids) who would then lead the bomber stream and mark the target - once the target was marked less able navigators could see the markers and fires and correct their positions. Once flying home, the navigation didn't have to be as accurate and a non chronometer watch was good enough.
One thing that confuses people is seeing watches marked with 6b/159 in which the /159 has been scribed out and 234 replaced. This occurred when movements were found not to be able to work to a suitable precision but still stable enough for general use and was fairly common. I'm told watches could go the other way, but I've not seen one.
By the time Bomber Command began to really expand, the American watches started to become very very common and you find every tom dick and harry wearing them, which is why they are as common as muck on ebay. If you want a watch that has seen air service from WWII then these are by far the cheapest route in and some, especially the Elgins have a truly lovely movement, the early ones even use an invar movement rather than mere brass and are arguably as good as the Omega (you can recognise them because the movement's plates almost invariably look as good as new.
Both Omega and the RAF built up quite a stockpile of the quality watches and movements, so there are a lot of 6b/159 out there with no marks. My assumption is that these were un-issued and sold off post war, but I've heard it argued that they simply were not always marked. I suspect this is just wishful thinking from those with un-issued ones. As for Omega's reserve of movements from WWII, just look at the random selection of thirty series movement to be found in their later Swedish Suveran watches.
So as a navigator with PFF, that's the right watch. It was the accuracy that mattered.
You will also sometimes find them with an HS8 marking, these were for Fleet Air Arm pilots and navigators. HS stood for hydrographic survey as it was their codes that the Royal Navy used. Obviously, given the type of flying done, these were issued relatively freely so are more common than you would expect.
*edit* sorry, I just realised I conflated posts one and two. I think that between them I got to the answer - /234 if it's 8.5 ligne or smaller and/or non chronometer then less able navigators (that's most of them) pilots and engineers. /159 - 10 ligne or larger and chronometer is high ranking personnel, navigators and fleet air arm. There were quite a wide range of makers, but Omega was amongst the largest.
That do?