Dermedicus,
The trouble with the 'Defend UK' in the Western approaches and North Sea argument is to define where UK's interests really start. Not considering where outside UK local waters we might need power projection for political purposes is short sighted. I am not suggesting that we need that capability to do another Iraq or 'stan but much of our energy (gas as well as oil) currently comes through the Strait of Hormuz; Somali pirates affect our imports and exports and there might yet be oil in the South Alantic. There are other examples where we are dependent on free passage on the seas. We need the ability to ensure those things continue, regardless of the attitude of others, if we are to keep the lights on and people at work. Whether the current and projected RN are what we need to do that I rather doubt, but 1SL can only work with what the politicians will give and hope that there is an opportunity to re-shape things later.
I see that you are in Oz. Some years back an academic called Dibb "persuaded" the Government (Bob Hawke as PM with Kim Beasley at Defence I think) that what the Strine people needed was a capability to defend Oz (in Oz' water/land/airspace) and that meant a more numerous but small-ship brown-water navy with more widely spread bases (as well as more widely spread Air Force bases). Dibb failed to consider all of Australias strategic interests and as a result of the rearguard action by those who better understood them Oz still doesn't have a small ship brown water navy (or a more numerous one).
N