According to the Belfast Newsletter of 23 September 1949, a verdict of “death from accidental drowning” was returned at an inquest in Derry yesterday on Frederick Isley, who lost his life in the River Foyle in the early hours of Wednesday morning.  James Fenwick, Stoker Mechanic in the THULE, stated that shortly after midnight Isley was going back to his submarine when he stumbled and his cap fell in the river.  In attempting to recover it, Isley bumped against him and they both fell into the water.

“Isley and I struggled in the water for some time.” said the witness. “I got arms under his arms to attempt to pull him out knowing that he was non-swimmer. but he wrapped his legs around me so that I could not move.  All that I could do then was to push him away from me.  I heard the THULE sentry call, and I thought that he had got hold of Isley.  I then sought to get hold of something myself to get out.” Stoker Mechanic Bernard Gant said when on sentry duty he saw Isley and Fenwick fall into the water.  He also jumped in.  He swam after Isley and caught him but the tide was too strong to turn and he had to go with it.  Isley started struggling, and he had to let him go.