I read in a book on the USS Scorpion that they have pretty extensive psychological testing for any USN sailors interested in submarine duty - even assigning psychiatrists to observe the crew during voyages. I'd imagine it's the same for the Royal Navy, so this really comes as a surprise. Not that any measures are foolproof, but this is still shocking. I wonder if he was just angry about his TOD, or if there was also a preexisting condition nobody diagnosed?

The USN did a project many years ago where they send Navy Diver type guys and Astronauts to a underwater research post. Well they called off the project after a man died because of a sabotaged O2 Regulator on his tank. Apparently one of the crew of the underwater base went nuts and started sabotaging equipment and nearly killed all the crew. It was called SEALAB I think.