Is this CR1 the same as the CR10 that you mention?
Sorry my typo, should have read CR1 card. CR10 cards were only issued between 1918-1921. They were issued under the Defence of the realm act. Without boring you with the details, the government of the day were wary of the Irish Independence movement and the ID number and photograph where supposed to nullify the perceived threat of Irish seamen acting as some kind of fifth column The CR1 card, which more or less gave the same information but with the exclusion of a photograph. Most cards CR1 1913-1920 have been destroyed.
If we look at your grandfathers CR1 card you will note a different Discharge A number R7840, Merchant seamen were not the best with dealing with bureaucracy and I suspect he lost the original.
Yet another Discharge A number appears on the CR1 R805836 This is erroneous as it belongs to a seaman born in Birkenhead in 1948!
What we really need is a copy of your grandfathers CR2 card, which would tell us which ships he sailed on from 1921. Sadly this seems to have been lost or destroyed.
You say he was DBS on MACEDONIA official number 116012 in June 1929. It would have been worthwhile to look at her logbook to see if there is any info there but this also seems to have been lost or destroyed unless it has been miss catalogued.
I note your grandfather was a Merchant Navy Fireman (Never, ever a stoker) by definition that makes him a "Hard Man".
These men worked in temperatures of 140 degrees plus, shovelling tons of coal, 4 hours on, 4 hours off, 24/7 for a pittance. Hard men indeed.
If you can get hold of a book called "No Longer Required " by Bill Linskey. ISBN 0 9537285 0 1. Read it. It describes the life as a Fireman on a British merchant steamship between the wars and during WW2. This book will make you laugh and cry at the same time. In my opinion, the best book ever written by a British Merchant seaman.
Bill, now passed on, was a founder member of Alcoholics Anonymous. His alcoholism directly attributed to his wartime experiences along with many other merchant seamen who suffered many untold traumas. The forgotten Fourth Service.