Hi Michael,
I was just browsing the naval medal records at the National Archives and it was mentioned on the page that:
"The letter 'R' over a code can signify that an application for that medal was reviewed and refused."
Here is the link to the page:http://www.nationalarchives.gov.uk/records/merchant-seamen-medals-ww2.htm
Hope that helps on some way.
Good Luck,
Adam.