As an apprentice Shipwright ,on 15the December 1954 . I was in my second year,we were gathered in the College For the Christmas Carol Service.
When it closed . We were instructed that we were to leave the college by the Main Gate, Not to re enter the yard. If we had belongings we were to leave them and collect them when we returned to work next. We did not know at that time that a disater had taken place just a few hundred yards away.
The caisson had blown out of the dock and the submarine inside was now stranded on the otherside of the river.
Also at that time unknown to me, my future father in law had just come ashore from the stricken submarine to make a cup of tea.
The link below gives an account from the Diver Involved.