By early 1967, Zuckerman’s interventions over nuclear policy from his new position at the Cabinet Office were becoming the cause of understandable tensions with his former colleagues at the MoD. We have already seen how his personal relations with Healey had begun to deteriorate during 1965 as Zuckerman chose to exercise his prerogatives by proffering direct advice to the Prime Minister over various aspects of defence policy. Zuckerman’s departure from the MoD in May 1966 was by mutual consent, but his subsequent pursuit of Robert Press’s services was not designed to ease his relations with the MoD’s central scientific staff, which was now under Cook’s direction.