[seafarer]

I'm betting on the British. Remember the iceberg sub/boat Bond escaped in at the opening of "A view to a kill" - little known fact that is that it grew out of the whole allied idea of giant ice ships. While "officially" the allies only experimented with pykrete and ice boats in Canada, British intelligence had their own plans in development (Q is older then dirt, after all - what do you think he was doing back in the 1940's?).