Ok thanks for all the help you have been providing.
Is it correct that if the leader fails to spot the enemy then the leadership value can not be used, even if firing with units in the same hex as the leader at a differnt target during the impulse the leader attempted to spot. (as the leader is marked with an op complete)
It's also why trying to spot is a "last resort" move. The consequences of not spotting are quite bad. I'd rather wait to see if the unit fires at some point during the turn and then open up the can of pain that the leader has assembled...