They are built by BAe (submarine solutions) in Barrow, the only yard authorised to build Nuclear submarines. I was there a few weeks ago and was amazed by the inactivity. I think there are only something like 2000 employees now, as opposed to about 10,000 in its heyday. I have plenty of stories about the place and the people who build the boats, but not here!
Yes they are expensive, submarines always will be, I was slightly flippant in saying they are all £1Bn a piece. The first one is, economies of scale will reduce the cost of the later hulls but not by a huge amount. If you think that is expensive, the first of the new generation destroyers (Type 45 for you Navy geeks/groupies) is coming in at about the same. Now that is a waste of money for a 'skimmer'- but please don't quote me on that
standing by for flak from Bumps
Do we need them? Of course we do, Govt policy says so! If we want a Trident replacement, assuming it is a submarine, we need to keep building them on a continous basis else the manufacturing expertise evaporates and you will never regain it. We are close with the US but not completely reliant. In comparison they have 56 Attack submarines to our 9!
But of course, who else would spend 50% of the defence budget if it wasn't for the 'gnomes' in Abbeywood!