To davidr,
Thank you for your response.I have checked the crewlists 1861-1913 and Thomas born 1854 was on the 1868 as a 16yr?- boy.
He was not on the 1874 list but Thomas Greggor 44yr- Master and also Benjamin Greggor 54yrs - Master are. Perhaps the transcription on"findmypast" is incorrect and should state 1873.
James