Well, Well, Well

I think I have found a well.  Between the two gardens at the back of the house is a 6ft brick wall which has an arch at the base (photo right).  I had seen this feature some time ago from the neighbour's side but on our side there had been a hawthorn tree growing right in front of this spot.  When I cut it down last year, I left two 3" stumps about a foot high; more recently, doing the groundworks for the extension, Colin pulled these stumps with his digger and they just came up without difficulty, because the tree had been growing on top of the concrete!  The arch then became more visible on our side when we removed the concrete slabs and a foot of soil (notice the tidemark on the wall!). 

I had been wondering if this brickwork could hide some water item such as a well or ditch, then we found a lead pipe under the tiled floor of the old extension.  Colin reckoned that in his experience this was probably the supply from a well.  He didn't want to rip it up at that time as there was still a live cast iron water pipe which might have been disturbed inadvertently.  This was the supply which fed my neighbour's outside tap (see previous), but it has now been disconnected so today I dug it up.  After retrieving 6 ft of two inch lead pipe (££ scrap), I realized that the bit left in the ground has an echo sound when moved.  Moreover, when I dropped a small stone down it, I'm sure that there was a watery sound.  The foul sewer goes in the other direction, so I think it is most likely to be a well! 

Presumably the wall was built over the well, and it was used during the 19th C by both houses.  Then at some later time the well was covered and the archway was filled in.  I think the important question now is how well was the well capped?  Or was the concrete slab (which covered the entire yard, 10' x 20') part of the capping?  The next question is how high is the water?   Do I dig out the rest of the pipe and see, or do I leave well alone?