Darling and Blackadder suggest that the push should be cancelled. Melchett responds by saying that would be exactly what the enemy would expect and therefore what they will not do, in order to make the Germans think that the British intelligence is rotten.
Darling and Blackadder recommend abandoning the planned push.  Melchett argues that this would be exactly what the enemy would do to mislead the Germans into believing that British intelligence is ineffective.