I vote for a ShinMaywa US-2. It has not four but five engines (eat that, P-8) of which four are RR and the fifth is half-RR. And instead of tossing expensive high-tech GPS sonobouys out from FL300 and hoping for the best, it can do what the PS-1 was originally designed to do - land on the open ocean and use a dipping sonar, which happens to be something that the UK builds very well. I suspect that would put the twitch up the commander of the best AIP boat out there.
It could be called the Sunderland 2...
