I think I read it correctly!
Hello Vernon,
You stated the following: "That Number i also think would be prefixed by the letter A ??"
I stated that I thought the number as it was originally quoted in the piece BT349 in Moya's post without the 'A' prefix was correct.
I suspect the prefix 'A' in that particular batch of surnames at Kew is marked so for a reason as it is not common for British seamen of that era to have a Dis A number of anything other than numerals. The prefix 'A' was to identify seamen from the Indian subcontinent but this is clearly not the case with the batch that includes I Campbell that you refered to. Once the numerical Dis A. numbers ran out British seamen were given an 'R' prefix in the early 1920's.
Regards
Hugh