I have just acquired a 4.2L S Type and one of the issues priced in to the sale price was the rear brakes. The EPB was sticking on and the PO was quoted $2200 by the Jag dealer to replace the EPB module and possibly the motor.
I assumed that the issue was corrosion in the EPB as a tap with a BFH would free up the EPB lever in the caliper. I ordered rebuilt calipers, pads and rotors that arrived today.
Once I stripped out the rear brakes the problem was obvious, the PO had the rear brakes replaced around 6000 miles ago by a local indie shop ( staffed by &%$#ing morons apparently ) and when they put the new pads in they got the inboard and outboard pads reversed. The shim pins on what should outboard pad now the inboard pad were against the piston and had jammed the piston preventing it rotating. The outboard pad that should have been the inboard pad, the shim pins had prevented the pad seating against the caliper fingers. This had put enough twisting stress on the caliper to jam the EPB mechanism and wear the pads into wedges. New calipers, pads and rotors fixed the issue. EPB works as it should now and no more strange noises from the rear brakes.