I don't know how one can get the GRAM pronunciation out of this spelling - and I say this as an American (where we usually pronounce Graham as above). The "ae" together definitely makes this GRAY-əm, or GRAYM.
Graeme Base is one of my favorite children's authors and The Eleventh Hour is my favorite picture book ever. I used to be annoyed by the spelling, but now I kind of dig it because it's different.