you could try an extending magnetic pickup.or one of those claw things but if that fails Camshaft out to recover the cap. Don't turn engine over until you recover it.
it is magnetic? get one of those telescopic magnets and try to get it that way, i dont know alot about land rover engines but id say get it out before you do any more. its not worth it. could mean a new engine or an hour of messing about??