"Aye - and what with the well/spring right near the church in Alton Barnes - and several other instances of well/yew/church (and likely pre-church usage of said sites) proximities - makes me wonder if there was once a connection... Hmm..."

Lots of connection, North Stoke church situated on the Lansdown slope (Bath) has a strong 'spout' of water that tumbles down by the side of the grave yard, the church might even have roman foundations, its right next to a villa, so if it was explored you could probably go back to its celtic pagan origins. There is a strong relationship between water and religious practice - pagan or christian..
And, by the river Avon at the bottom of the hill, there is a saxon cemetery, bronze age burial mound, and the church nearby is reputed to have a 'pagan temple' - probably a roman shrine by the river....
And, just on the outskirts of Bath, a stream that Rhiannon knows well, had a pair of celtic spoons (presumably for baptismal purposes) found nearby and 'stones' were also marked on oldmaps next to the stream....
history, religion, water flow together through time ;) Celtic saints would have baptised at the wells and the churches would then be built, but I bet the so called saints were in the business of 'taking over' the shrines of the pagans and stamping there own authoritive god in the place of the old gods......