Came out about 1963-4, and was sung by a boy of about 14 (rather like Laurie London but I don't think it was him)
the lyrics went:
I know, whatever I could do I've done,
I say that you're the only one,
xxxx The reason why -iy - iy
And I know I'll always love you till the end
.... cry-iy-iy
another verse went:
I know. whatever I could be I've been
Have a feeling his name had a Graham in it, not sure whether that was first name or surname.