Yes there were a number of break-in's at the time, however anglers were allowed to park where the rangers hut is now placed. This minimised the break-in's. This isn't really a problem anymore, although I hear it's a dogging hotspot these days. Not that I have been involved

I used to walk down from Old Brampton. Incidentally who was one of the original members that you spoke to as my father was also one of the founding members.
The person I spoke to at Severn Trent was a chap called Steve Pogmore who works in the estates department at Derby.
There are some very nice Perch indeed in the middle res. As for the bottom one, I saw a shoal of Roach in there a couple of years back and it must be well over 10 years since it was last stocked with trout so I'm sure they will be long gone. It was a bit of a shock seeing the roach as I have walked around all three ressies over the last 25 years and never seen anything except trout and perch and minnows in the top dam. The bottom res was virtually bone dry last year so I don't know if the Roach survived.
If you want to pool resources and try for permission again then let me know.