I have a Vertex,15 jewel, half hunter style, Star Dennison pocket watch which I am trying to date and value. The face bears the legend Vertex, Swiss made and at 12 oclock the word 'Chester' and another word which has faded to be unreadable. Inside the second rear cover are the words 'English make', this case guaranteed to last 10 years and the numbers 185184 and under that 33C.

Inside the rear outer cover is stamped Star Dennison 185184 and lightly engraved, 27576. 4231/10 and 77920, followed by a signature which is unreadable. The front cover has a bubble glass centre and is stamped 185184.

Can anyone help??