P-8 inside, out and attacking a Kilo class sub.
Patrick Wintour, UK Guardian, November 23, 2016 now reports:
See additional details concerning the P-8 decision and implications on bases in Britain at http://www.bbc.com/news/uk-scotland-north-east-orkney-shetland-34898079.
A further advantage of high and fast operation - it should not be forgotten that P-8s used by the US, India , by 2017 Australia and soon the UK also have a major ground surveillance mission. In this mission low, slow flight mode would be inefficient and leave them vulnerable to surface to air missiles.