We have spent some time looking at the reservoirs next to our mooring. The area was changed when the canal was widened in the 30s. There is a map dated 1886 which shows what the arrangement was prior to the 30s. You can see that here
http://maps.nls.uk/view/101585599Of interest to us is that it looks like the reservoir had been extended prior to this date. The feed to the reservoir is from the Oxford Canal just to the west of the junction and the feed from the reservoir heads to below Calcutt Bottom lock. You can also see the dry dock to the west of the top lock.
There is also a lift bridge between Napton Junction and the top lock plus, what appears to be, a stop lock at the junction.
At some time, probably during the 30s the feed from the Oxford Canal was replaced with one form the Warwick and Napton Canal. This is about 2 boat lengths from our mooring.
The current Google maps shows the old feed as a mark in the field. See
https://goo.gl/maps/JYUUpThis is the new feed.

And the working platform.

It is automatically operated depending on the level of the canal but there is a manual back up.

The causeway that crosses the reservoir makes me think it has been extended.

By the way you can see the corner of our boat just sticking out above the bridge!
At the end of the causeway there is an area that used to be used for a local sailing club.
There is a series of stones let into the ground.

This is the slope for launching.

There is an old winch with brakes at the top. It even has brake shoes in one drum.

We also found a mysterious piece of railway track. (And Jo's mysterious shoe!)

Following the embankment round we came to the site of the old feeder. This is now an overflow weir which feeds to a ditch at the bottom of the embankment. This area has been recently dredged.

Returning to where the reservoir feeds the canal, there is a platform (which the local kids use as a diving board).

This is also automatic based upon the level of the Stockton Pound.
There is an exit from it at the bottom of the embankment.

And a rather intriguing tunnel just above it. This is less intriguing manual control inside reveled by the camera flash.

The feed continues through Calcutt's wet dock to the marina.

Above Calcutt top lock is the back pump feed.

This is operated when the Stockton pound is above a certain level and the pound above the lock is below a certain level. Potentially water can go round in a circle via the reservoir and back pumps!
Also by the top lock is the old dry dock.

And the old narrow lock by the water point.

This brick building is shown on the old maps and has a decent padlock on it but what does it do? It is at the end of the embankment near the canal.

The reservoirs store water for the canal beneath Calcutt locks not for Calcutt locks so i guess it is used to make up for leakage/evaporation from Calcutt down to Leamington.
Well we had an interesting afternoon.
Cheers Graham