seems i was right.....
Anybody who has ever had chickenpox can develop shingles, and most people do have chickenpox in childhood.
People who have not had chickenpox cannot get shingles (some people with shingles claim that they have never had chickenpox - but this probably means that their original bout of chickenpox was so mild that it was not noticed (sub-clinical) or that the patient has forgotten because it was so long ago).
http://www.bbc.co.uk/dna/h2g2/A3022525