Interesting that in this whole thread nobody there has only been one passing mention of the aircraft which actually did drop nuclear weapons, ie the Valiant. A number of weapons of differing types were dropped during Operation Grapple at Christmas Island in 1957 and 1958. I suppose it is understandable that since they were withdrawn from service in 1965 the Valiants have become, to some extent, the "forgotten V bomber", but they do hold this unique distinction, if distinction it is.
In the 70s it was decided that bomb doors should be opened manually somewhat earlier in case of unknown battle damage or the failure of one of the hydraulic pipes.
Somebody had obviously been watching Dr Strangelove!