The RN should consider purchasing some type 214 submarines, which compared to Nuclear boats which I served on are very cheap and need only a crew of 28-30, they are extremely quiet and can stay submerged for up to 16 days and are ideal for coastal work. The USN has chatered one initially for a year and now extended for a 2nd year(The Gotland) to try and work out a defense against this type of submarine, so far with little sucess.I have been involved with the 3 type 214's building in Greece for 5 years and I find them very impressive in both quietness and diving depth.
You might want to revisit your claims - there's a whole pile of factually incorrect material in your post.
and before you get defensive - there are 4-5 ex submariners in DT, there are probably a similar number who are ex/curr industry and who have a close association with building subs.
on top of that, some of us have actually worked on a firsthand basis with the boats you're waxing lyrical on
As per Bonza's comment, you need to moxy up with some proof of your priors, because your current commentary in some areas is a direct contradiction of what some of us do know about subs