I know CinC Bomber Command had the authority to launch if contact was lost with the Government.
I also know that the Command exercised full force generation with live weapons twice per year.
I also know that the CinC, during a NATO wide PCX ordered full force generation 3 days in advance of SACEUR bringing NATO assigned nuclear forces to full readiness.
What I do not know is if the CinC was authorised on his own authority to bring the force to Alert Condition 3 as he did twice per year. If that authority was so delegated then it is possible that he had brought the force to readiness before MacMillan so ordered.