I'm afraid there's been a long gap since my last entry, I've been researching various sources.

The only information I have is that the vessel did have strong Norwegian connections, although I would have thought the loss would still be on record.

I have used the date of his hospitalisation to assume the date of the sinking, but it is possible the two items were unrelated.

One new fact I have found is that military gunners posted to merchant shipping were listed as merchant seamen, usually deckhands. So if the ships records are Norwegian he would appear as a civilian. Apparently in the U.K. records of postings between the military and the merchant navy tend to be very poor. However, I still have hopes of identifying the vessel.