1920's rose gold ladies Rolex - unmarked dial

[Loz]

Hi, this is my first posting - so please forgive any gaffs!

I have discovered that a small gold watch, given to me by a family member, is an old Rolex, tho its face is unmarked. I flipped off the snap on back and discovered beautifully stamped works and the back plate contains lots of clear info for research. Condition is good and the face glass is unmarked but the case is a little grubby.
The watch is working and I would like help identifying its age etc. I have googled for info and know a little about the history of Rolex, its beginnings and so on. I have attached photos and would be grateful for any information from near or far! Thanks for all informative responses!

[TheBluePrince]

Here's anohter one just sold on Ebay, same same but different.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWAX:IT

[Loz]

Hi, and thanks for the response - I have seen this old Ebay sale and noted the differences between the two watches. I thinks mine may be earlier as I read in various Rolex Histories, that W & D is stamped on the earliest back plates. There is an import gold mark and a date letter 'g' London 1922 and there are no hinges. I understand the company moved to Switzerland around 1919 - does that account for the import stamp?
The sunburst dial numbers are all in black - what is the significance of a red 12 ? and the dial has no name marked - shame but hence its obscurity and being forgotton in a drawer!!
It would be fantastic if the watch's beginnings could be identified from the info on the plate and the mechanism.
That's why I'm hoping someone out there can kindly enlighten me or advise where to look.
I'm a busy gal - but this watch has got me soooo curious!