Hard a starboard, no port, Oops! Luvvit! With so much traffic, its amazing it hasn't happened before, but it has, in the case of subs and trawlers, often will tragic consequences.
This could have been another MOD cover up, annoying that we found out about this from the French and not our own navy, we should by rights notify all allied navies if we are in the same area.
Note: Use indicators next time