Highflyer, as I recall both of the submarines were strategic missile submarines, I always thought that their job was to keep out of the way of everything else to give themselves time and space to launch on order. Yes in the days of the Cold War there were collisions between NATO attack submarines and Russians, a very different set of circumstances.
The fact that they did collide in my view says either that the passive sonar that is meant to be the ears of the sub was not as good as it was thought to be or that both subs had better sound deadening etc than was normally expected.
I have a feeling that most Naval commanders who's vessels hit something normally get relieved of their command for risking their command, I never heard of anything happening?
The collision was reported to have been with a container that had been washed off a cargo boat to begin with until it became apparent that two submarines one French and one British had been damaged on the same day.