I've talked with RN submariners who visited our homeport. I would certainly call them more skilled than the average USN submariner; they have a much smaller cadre and spend a lot more time on sea duty since they don't have to follow U.S. DOPMA requirements.

However they don't have enough spare submarines lying around to just convert one like the U.S. did for Halibut, Parche, or our current special projects boat.