Vic going back a spell this was also by you .
I wonder if this will help at all by looking at the Crew Lists for the Ship
This Covers Home Trade for 1942 . So he should be listed in the Documents ,and you may then be able to see what date he joined ?? Only guessing on that though
Cheers
162500; 162501; 162502; 162503: 162508; 162510 | The National Archives
before the allocation of prefix ‘R’ Dis. A book numbers they were just numerical and certainly by the mid-1920’s had reached 7 figure so thee wee those with 7 digits !