Jaguar Repair: Seized engine, cam chain, bell housing

Question
I understand the crank does not turn easily but I used a 3/4 inch breaker bar and a cheater pipe and it would not turn.  I did pull the starter and bench tested it and everything works fine.  To turn the crank I did remove the fan and shroud so that I could get some torque on it.  What could cause the motor seize right after being ran with no signs of a bearing failure (no knocking or any noise).  All fluid levels are fine and there is no hydraulic lock (plugs were dry and no coolant in the oil).  The temp on the car prior to shutting it off was at normal operating temp.  At the moment I have the starter out and attempted to turn the flywheel with a screwdriver to no avail.  I do not have a large enough pair of channel locks to try the water pump method.  I am trying to find out is there something I can do besides pull the motor.  I dont have a lift to pull the oil pan so I cant check if any bearings are froze.  Could the cam have locked up freezing the the timing chain and therefore crank?  I was looking in those screens on the bell housing but I do not see where to turn the crank.  Thanks again for all this help.

Answer
Working in dealerships we would at times get a locked up engine and I always found that if it was piston related then you could get a very small free movement of the crank back and forth. (Rod bearing clearance) But if it was crankshaft related, the crank seemed like it was welded solid. (A broken cam chain can do the same) To check the cam chain just remove the cam covers and try to force one of the cams back and forth.

Did you notice what oil pressure you normally had?

Howard