Climbing as a pair on a hot day at Stoney, knowing that the nature of the limestone there was more rounded than others. I led up the rope using twins ropes and having selected primarily cams and medium to large nuts following an assessment of the route as obviously crack oriented. I led up the route making good progress to the top/final move of the climb. I recognized the risk presented by the small ledge below and also that I'd need to move right around the large hanging block into an unknown position with unknown gear and holds. Foot holds looked poor so it would be pumpy. I had protected above the ledge but also place protection with my left rope into the crack on the left of the large block - it fit well. I then moved left into a grubby part rock, part soil crack big enough to torque my torso into but I had to maintain a right hand hold and my right side was committed into the crack. I spotted a poor, flaring placement for a number 1/red cam but couldn't see other places that weren't rock on soil. I spent quite a lot of time and thus energy trying to make the cam fit and was getting quite pumped. I noticed my breathing increasing as panic unconsciously crept in. I took the time to call my breathing so I could focus on the placement, a number 2/gold might be better? Nope on my right hip, not an option. I fumbled more with the cam getting it clipped and trying to improve it but it wasn't great and moved around. Real fatigue was now setting in and I was force to make a move up or keep pursuing bag gear choice. I didn't feel retreat was a less strenuous option as it would mean a boulder move to get back around the bulge and the end of the climb was in reach. There was an ok high left foothold and and a poor low left hand crimp - but I was sweating heavily. I took the decision to commit in a bit of a panic. Went for the move, slipped, inverted and my pelvis hit the ledge and I was left hanging upside down below the ledge. Total fall circa 3-4m. I was lowered off and with the help of my belayer and 2 friends we got my harness off and I moved to a place where we could assess injuries. It looked ok until I suggested a lump on my back and we took the decision to call mountain rescue. They were there very quickly and due to the risk of spinal injured trussed me up good on a spinal board and got me out to await the ambulance. The ambulance crew took some time getting their due to business and location but they managed me and my pain along with the paramedic who'd come with us. We got into Northern General hospital where I was met by a trauma team who rapidly assessed me and got me into MRI and MRI with contrast media. I was then seen by 3 different orthopedics doctors who gave their opinion that whilst I'd sustained multiple fractures to the sacrum surgery wasn't a good option and that rest and recovery would be best and neurological damage seems to be minimal. I was very lucky to be surrounded by caring friends and the excellent members of the emergency, hospital and mountain rescue services who got me out of a bad situation and have got me onto the road to recovery.