Yep Tony it is all part of the Dearne Valley area, all that area was full of coal mines.
I don't think the RSPB own it but manage it, I think it's designed as a flood plain for the area, there is a bridle/footpath that runs all the way round it, they have gone to a lot of trouble to put predator fencing all the way round and it looks like it is going to pay dividends when it comes to the ground nesting birds.
My Flickr photos
____________________________________________________________________
Regards,Tony
My Flickr Photostream