Simple answer to all the air-launched possibilities discussed above is in Wednesday's MoD News Release:
'Defence Secretary Dr Liam Fox has today announced that approval has been given for the early phase of design of the submarine that will deliver the UK's nuclear deterrent well into the 2060s.'
The bit about alternatives is covered later:
'The Coalition Agreement reflected the desire of the Liberal Democrats to continue to make the case for alternatives. That is why the Defence Secretary has also announced the initiation of a study to be undertaken by the Cabinet Office and overseen by the Minister of State for the Armed Forces to review the costs, feasibility and credibility of alternative systems.'