I'm sure there are those who know more about this than me but I can offer this. The Well Chapel is next to the spring where the Little Stour rises. A quarter of a mile below the spring the Little Stour is joined with the less than reliable Nailbourne. Judging from the mills on the Little Stour at Littlebourne, in Nargate Street, at Wickhambreaux and at Seaton the Little Stour has long been vital to the economy of the area. So I am guessing that this was an important religious site for a long time.
Although the chapel is away from the main road it is on a footpath that was certainly there when the railway was built because a large tunnel was constructed in the railway embankment to let the footpath through.
Has the site every been surveyed or dug?
John