The gun Fab illustrates is a transitional model, built before the V model we recognize today became the only V model. Regis Darne patented several new designs in 1909, which, were built alongside the older versions for some time.
A good, clear photo of the flats of your guns barrels would help immensely in narrowing down the age. Markings came and went at the proof house as laws changed, and seeing what marks are there is more important than the serial number from a date of manufacture perspective.
That is a beautiful V20.
Best,
Ted
