Thanks seaweed, interesting stuff. What I have is a letter from the Ministry of Transport and Aviation saying that he failed to join the Waimana and they had no more information. I also have his discharge book using a reference that I got from the letter. I will definitely look into logbooks etc
great advice. The story that I have been told is that my Grandfather was on the same ship and he joined but Cecil did not and he never knew what happened to Cecil.
I appreciate the advice. 
You should be able to view the 1950 logbook/s and crew agreement/s by a visit to the British National Archive in the piece BT380/478
http://discovery.nationalarchives.gov.uk/details/r/C10965355Most archives catalogue logbooks and crew agreements by the vessels official number.
If your grandfather was on board that will be recorded in both documents.