The Old Bishops Palace was surrounded by a moat in the Medieval era. Moats were a status symbol for a mansion. Moats like these were not a serious military deterrent, though households inside a moat were more secure than otherwise. The main fashion for adding moats to properties was from the 1100s (The Anarchy) – when the defensive merits would have been important – through to the Tudor era and later, when it was mostly for prestige.
By the end of the medieval period, though the Palace was “mostly surrounded” by the ‘moat’ (as quoted in 1756 national newspaper articles about the rediscovery of the Well) it was actually spit into a number of fish ponds, spread out in a ‘d’ shape. It was the maintenance on one of these ponds, de-silting it, that lead to the Chalybeate waters being spotted.
The fish ponds were normally stocked with fish such as pike, tench, eels and bream.
Fish ponds, and their fish, were very important for the medieval diet – especially ecclesiastical households, were meat was not permitted for about 150 days of the year, which the Bishop and his household would have complied.
Freshwater fish would be given as gifts, to royalty and liege lords. In 1461, the household accounts of the Bishop of Coventry and Lichfield lists that they paid for ¼d for herring, but 6d for tench.