These will be conventional rather than nuke though? The aussies should have gone in with us and bought a couple of Astutes. More effective and if the Commonwealth (or at least the none mickey-mouse countries within it) did this there would be considerable savings due to economy of scale efficiency...
Nuclear propulsion is still too controversial here. I know that doesn’t make much sense from a scientific or engineering viewpoint, but it’s a political reality. We’re not going to get nuclear submarines in the short term, so we need to get the best conventional submarines we can.