Not only that, but a defence expert said that the lower the water gets, the more of the submarine's secret's may be revealed!
I believe someone (I think he was an ex-submariner) who had lived locally for some years, and who took pictures of the stranded sub, said that this happened occasionally as it was a training area.

He believed the RN when they said there was no danger from the nuclear power plant and that well rehearsed proceedures would have been put in place.
This was naturally a bit of embarrassment for the RN, but these things happen - not being helped by tidal currents and even the wind. Of course there is always human error, even in highly-trained organisations.
Alternatively, perhaps the helmsman had just heard the latest news of the defence review?

Dare I ask what happened to you Tony, or would you rather not talk about it... ?