Perhaps my maritime colleagues might be able to shed a bit more light on that. I'm not a submariner by background.
As a force employer, I can tell you this. As you've seen over the past number of years, the submarines operate during the open season in the approaches to the north. They're a conventional diesel submarine. They don't have the capability to operate under ice, as other platforms would, but they are certainly very capable up to and including that point.
I hope that answers the question, sir.