I take your point and I do agree that it's very hard to determine precisely what amount of military might can be regarded as being sufficient to protect one's own country but I'm sure you can see what I'm getting at?
There's a very big difference between addressing the defence of the United Kingdom (including our offshore interests which Al mentions) and the desire to engage in all manner of global conflicts which ultimately have no connection with our defence. What on earth are we pouring huge amounts of money and manpower into Iraq for? Has our presence there saved so much as one British life? Nope, it's actually lost quite a few. Likewise, has our presence in Afghanistan helped to make us any more secure? Nope, it's resulted in the needless deaths of British servicemen. What an earth are we doing? Unless I'm missing something very obvious, I thought the purpose of our armed forces was to defend the United Kingdon, pure and simple, which is why I have to question what possible motives we have for maintaining a significant surface fleet.