a few years ago Deb Limbert and myself surveyed Perfidia and looked at the leads towards the end with assistance from Lugger, Mick Nunwick and Robbie Burke.
After the long flat out crawls you enter a succession of domed chambers. In the side of these a small extension was found, but with no obvious way to extend.
At the far end the furthest point goes through a tube that has been dug out into a small chamber with a tube continuing that looks like it has been dug. The problem is that where the clay has been removed from the floor, water has now filled the space. we visited this area a number of times to look at some leads just before this point and each time the water level was the same meaning that to dig this would require it to be either baled or pumped first.
Approx 10 metres back from the end is a chamber with what appears to be a small streamway off down to the left (looking in). Downstream goes back parallel to where you have come from and joins a crawl from a previous chamber. The opposite way heads parallel to the final dig, but looked a more difficult proposition than the draining the end.
The survey did reveal some interesting things - the passage runs parallel to the main drain and does not cross it as shown on an earlier survey. The end is not as far as previously thought, but is approximately 400 metres from Rushtons chamber and finally the reason we were interested was that it has not yet passed Greta junction - a point at which the main drain undergoes a significant change.
If you are going in look out for the weather and as winter comes on expect some long cold ducks!