The following is highly speculative.
As part of my ongoing exploration of Coventry's waterways and mills I found an anomaly at Charterhouse. The area south of Gosford Gate used to have many meanders that were subsequently removed. At least one was blocked up by the construction of the railway and the river channel going under the arches is quite probably new. The oldest maps chart a few of the original loops but the river in front of Charterhouse is suspiciously straight in every map I've seen. Of course the monks themselves could have created the current channel as other monks did across Coventry and it seems a roll of the dice whether the linear mill race or the original channel remained after the mills were removed. I've mentioned that I'm missing a mill and while the most likely answer is that the mill was actually the same as another mill (they had many names over the years), there is a possibility that my anomaly is the missing mill pond. Here's a map of the anomaly. It's the wiggly line starting middle left and ending with bushes/trees bottom right. Probably it's the remains of a stream bed draining off the common (now the London Road cemetery).
But there's another feature, the oblong nearest the lane to Charterhouse. Just a modern field boundary? Except it's visible in this aerial photo of war damage (thanks Robthu).
And seems to be a lower stretch of land.
So, was this a very old meander of the river that has long since silted up? There is a claim that outside Charterhouse, surrounded by water, there was a chapel for ordinary people. The current river route and an original meander (rather than a stream) could have created an island. The land on that side of the river was called St Anne's Grove.
The dark blue line is the river as per my oldest map.
The pale blue line is the river feeding Charterhouse mill
The green blob is the mill location
The green line is the wiggly feature
But what is the oblong feature? If we look back at Naul's mill we might have a clue.
Notice the wider straight end to the pool? Water was channelled off to fill the pool, while the Radford Brook continued along its original route. The mill pond wasn't pond shaped and the mill was furthest from the straight feature. Could my anomaly be a similar thing? It would still have left plenty of space for a chapel. A mill could have been anywhere along the wiggly line before it joined the main channel. One fly in my ointment is that the land may be too high to have been fed by the river nearby and we're back to the stream idea. However, as with Naul's mill pond, water could have been tapped off further up the river where the head height worked. Most of the traces of this feature could have been silted up, ploughed out and filled with organic material. Even the land level would have risen. In the Google picture I drew in a very speculative red dotted line for a meander but water channelled off could have been well off the map to the north.
One last thought. The lower land closest to Charterhouse and next to the current river route was called The Dove House Meander. Might the river have come much closer to the buildings? Time, silting, new channels and man have left us with just guesses.