With the chain guides so tight to the crank sprocket the chain couldn't have "slipped off" there. I think the only possibility that the chain could have been slack would have been when the injection pump was first changed if the FIP sprocket "dropped". It went from a superb running engine with a leaky FIP to an absolute pig that stopped every couple of miles. I've now changed out the chains and guides myself but without removing the head, so I didn't get inspecting the piston crowns. The additional defect now appears to be the collapsed torsional damper. - I just started the engine to move the car, (only 40 seconds running ) and found the steering jerky. I felt the crank pulley and its very hot! So yet another part now to change. I have ordered a new pulley which is also fitted to the BMW 325 from 1993 (the BMW equivalent is £70 v hundreds for the Landrover part number).
You've had the crank bolt undone? That needs some serious torque on it. Sure Wammers said it drives the oil pump but only if done up tight enough.
Crank pulley has rubber damper in it and the rubber sometimes breaks up. Could be that? It should unbolt without touching the crank bolt.