PN IIRC from Hennessey, the PM had 2 nuclear deputies....if war was looking inevitable, these would be identified to the Joint Chiefs and CinC Bomber Command to notify them of their identities.
Should the PM be killed, then one of the deputies was authorised to order to release the V Force-if contact was lost with both deputies (one in London and one at Turnstile) then the CinC Bomber Command could authorise release of the bombers to their targets.
No letters of last resort prior to the Polaris boats as far as I recall-its been a while since I read Hennessey though...
It would be interesting to know the Chain of Command now and whether Mrs May has any nuclear deputies-especially as her letters are still in number 10 (possibly) or only in the safes of the boats not on patrol....
Last edited by Treble one; 20th Jul 2016 at 20:48.