It may be possible to confirm family relationships by comparing test results with Graeme or other carriers of his ancestors' Y-chromosome or mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree:
Family Tree DNA Y-DNA Test 12 markers, haplogroup I-M253, FTDNA kit #B80905
Mitochondrial DNA test-takers in the direct maternal line:
Family Tree DNA mtDNA Test HVR1 and HVR2, haplogroup V, FTDNA kit #B80905
It is likely that these autosomal DNA test-takers will share some percentage of DNA with Graeme:
AncestryDNA, GEDmatch A615544[compare], Ancestry member GRAEMET188