remove the plastic cowl and on most cars(dont no a lot on rr) you can see the barrel clamp and top of shear off bolts either drill off head or a good punch,hammer and abit of time. you can unscrew it.
Get an 0-80 tap, appropriate tap drill, an 0-80 screw, and pin vises. Drill a hole into the fattest part of the end of the key. Tap the hole. Drive the screw into the hole. Grab the screw head with pliers, and pull the key out.
But that's just me.