the one i've only seen from a short distance away was here -
http://maps.google.co.uk/maps?hl=en&...ed=0CBkQnwIwAA
as you look down the hill, it is in the hill to the right.
buddah has posted a link to the 2 vent shafts i was on about that have now been capped in this thread here -
http://www.nwex.co.uk/showthread.php?t=7619
as for the other entrence, there is only poor quality pics on google earth, and i cant quite work out what is where, but for a rough idea for now, the bloke on the right of the picture in the link buddah posted is pointing in the direction, there was a wide entrence with a pile of mud / soil in front of it in the side of a steep hill if you walk in that direction,, the pile of mud looks like landslide that ran down and landed in front of the entrence, i should point out though, it was a good 15 or 20 years ago we used to hang about on there,
the one i've posted a google maps link to above, i saw earlyer this year while up at dovecote tower