It does appear to be a nice example, though the lugs appear to be a bit...funky. It would not be easy to place a value on it, as 9ct gold is generally not of strong interest to collectors. But that's what auctions are for...
Not sure why you think the case was made by Borgel, although it is in that style. It is clearly marked as being made by Dennison in Birmingham between July 1936 and June 1937.
I cannot recognise the dial material from the photos, is it enamel?
Wrist watches sold in England often were in Dennison 9K cases, and dependend on the movement the values can be quite significant. For example, if an English-made Rotherham movement is used (with whatever signature), the value clearly is in the 4-figure range. "Normal" Swiss import movements typically struggle to reach mid 3-figure ranges, because not really rare. However, this one seems to be especially nice.
If it is with an enamel dial, I might be interested and you may contact me as soon as you have developed what a fair value might be.