Fascinating discussion but noone has yet answered the question of what are you going to throw a nuke at these days. There was a logical reason for having them in the days when there were two sides, each with enough nukes to make the dust bounce several times over. But now?
Who is likely to use them and have something worth while to throw one back at? Pakistan and India? Can't see HMG responding to that should they decide the question of Kashmir cannot be decided on a cricket pitch.
North vs South Korea? I would have thought China more likely to step on that given the risk to its economic growth.
China and Taiwan? Should China finally decide that democracy on its doorstep is not conducive to keeping the masses in place then its a possibility. However, is the RAF going to get orders to fly to the other side of the world to participate in something that may be of marginal interest to HMG? I don't think so. Far more likely a SSBM as it could probably drop one (of many) without going far from home waters.
Middle east? Can't see anyone getting involved there until both sides have sufficiently massacred themselves and then only to clean up the mess despite the effort and involvement in Iraq.
Jimlad
I was recently told (third hand) that at a certain "joint" space research base not far from where I am writing this that Mr Gates' finest products are not allowed anywhere near their computers where the continued operation of them is critical to the base's mission.