"Nothing in this Manual prevents controllers from using their discretion and initiative in any particular circumstance"
I've always believed this to be an admission that the MATS cannot allow for all circumstances or the unanticipated effect of a series of events. It is only when practical experience has brought to light the danger of a particular combination of actions and reactions that definitive procedures can be written to prevent a reoccurrence. The provision of radar services outside controlled airspace seems the most likely area these sorts of situations can arise.
But what if the ATCO follows all the correct procedures and fails to spot the flaw. Does the above hold him/her responsible?
Saving grace or sting in the tail?
Incidentally, after quick look in the LACC part 2 I cannot find any similar entry.