Following two independent reports of a large underground bunker at Ambergate in Derbyshire I popped up there this weekend for a brief look around.  About 100 yards from the ROC bunker (towards the road) is the following structure

This is on the highest land in the area and according to the locals is something to do with Severn Trent and a large underground pipe line.  The doors are substantial steel plate with a heavy padlock.  One of the small glass panes is broken and I managed to take the following poor quality picture through the hole.  So it is simply a valve building or something equally boring.

Continuing on past the ROC bunker and further down the hill (about 150 yards the other side of it) I found these:

There are four of these in the field.  Each one is approx four feet across and padlocked shut.  If they are access covers to water pipe valves or something then the pipe must be very deep because just past the trees at the far end of picture one is a 100 metre vertical drop with an established wood growing in there.  There is a sewage plant in the valley but if these are something to do with pipes feeding the plant then they must be at least 100m deep.  The filed is quite a bit higher than the surrounding land, the pictures don't show this very well.

My parent live in Cheshire and the water board up there have just converted one of their old reservoirs into something else by cutting a hole in the side and inserting a roller shutter.  Could this simply be an abandoned reservoir?

Well I now know what the building is.  I am currently working on a building project which is on a piece of land which is crossed by the Derwent Valley Aquaduct.  This is a 29 inch diameter water pipe which runs from the Derwent Valley all the way into Nottingham.  The building is the top of a siphon which runs down the other side of the hill.