Unfortunately, I don't have the local 1912 records yet, so am unsure who exactly was in the area - I'm hoping they will be placed online in the next week or two. However, Dover was awash with Territorials in the few years before WW1, so it may well have come from a temporary tented summer camp. I think Scotchie has a photo from the area of Whitfield Ave that shows such a camp around there at that time.
It's hard to be certain though. Although made in 1912, it could have been dropped a year or two later. It's so corroded, I'm having trouble making out the complete headstamp. So far it looks like '? G12 VII'.
The old Heinz 57 varieties and a good rub followed by some Brasso does wonders: