Hello Robert, we are neighbours! The Lady Well
This plaque (my photo) shows the original source of the ancient Lady Well, now under No 149 Ladywell Road.
Lewisham was founded in the 6th century by a pagan Jute, Oleofsa, who, after burning his boat, settled near St Mary's Church, Ladywell; so Lady Well almost certainly had pagan origins. In 862 Lewisham was referred to as Liofshema mearc, then as Lieuesham in 918 and, in the Doomsday Book of 1086, as Levesham.
In 1986, Robert Smith published The Well of Our Lady (The Ladywell Village Society, London, England, January 1986). In it, he shows how the sacred well was recorded as early in local records as 1472. Smith notes that there has been a Christian Church near the site for over a 1000 years, and that in the past, the well was dedicated to St.Mary, and was visited by pilgrims on there way to Canterbury. The dedication to St. Mary also fits in with the many other examples of Christianity taking over Pagan sites in this way. Sadly, the well is now covered by the road over the bridge by the entrance to Ladywell station. (That is not where this plaque is!)
Chris Street never says much about London south of the river, his stomping grounds are mainly on the north bank.
Anyway, if you ever want to do some dowsing round & about - give me a shout.