How deep?

I went for a walk from Huggate, on the Yorkshire Wolds. Although it had rained heavily in the morning we were lucky and did not get rained on during our 2.5 hour walk. I spotted this marker on the village green in Huggate, although there is no other sign of the well as it must be 'well' capped off. Evidently at 348 feet deep it is among one of the deepest wells in England.