Methodology

Some other Swiss watch makers (eg Longines) have detailed records of every movement they produced and a watch can be accurately dated from this alone. The West End Watch Co. were also meticulous about numbering their watches, though the number is usually on the case back rather than the movement.

Unfortunately they don't seem to have been so meticulous in keeping the records matching the serial numbers so it's not possible to directly date using them. However, with some assumptions, a lot of watches and some luck it will be possible to build up a database and make it possible to get rough dates for serial numbers. 

The Assumptions

• The serial numbers are sequential. (That's a biggie)
• As the number is on the caseback there is a small risk that over time, as dead watches are used for spares, that a caseback can end up on a different watch to it's original mate. I make the assumption that this swap rate is low enough that, on any given watch, the chances of it being swapped are very very low.

The Watches

While I'd like to use only watches I owned, or at least had handled, realistically that's not going to produce a large enough sample to get a meaningful result. Luckily, in the days of the interweb, seeing high quality pictures of lots of watches is very easy, thanks almost entirely to eBay...

The Luck

Even with lots of pictures, you still need some external references to match a date to a number. There are several obvious methods we can use: inscriptions, catalogues, adverts, receipts and other documentation, perhaps even old photos.

In lieu of the above you can also attempt to roughly date a movement from it's style and features, though this is unlikely to be more accurate than to within about a decade.

The Bad Bit

I'm going to come immediately unstuck here. It actually appears that serial numbering was somewhat haphazard and at least the watches with Longines movements follow a completely different numbering scheme. Furthermore, some watches have a stamp that appears at first glance to be a serial (two sets of four digit numbers, sometimes prefixed with a letter) but actually is more like a model number and/or import mark and the watch may or may not have a serial number also stamped beside it or elsewhere.

Oh well, lets carry on regardless and see what emerges...