Perhaps you should try some spelling variations:
"a duncan smith" » "a duncan sarah", "a duncan scott", "ra duncan smith", "_ duncan smith", "j duncan smith"
"john duncan sir" » "john dunton sir", "john dunning sir", "john duncan i", "john duncan sarah"
"jon duncan sir" » "j duncan sir", "ian duncan sir", "colin duncan sir", "jon duncan i", "jon duncan sarah"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("a duncan smith") OR ((("jon duncan sir") OR ("john duncan sir")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"a duncan smith\") or (((\"jon duncan sir\") OR (\"john duncan sir\"))))".
• Removing quotes may allow a broader search: (( a duncan smith ) or ((( jon duncan sir ) OR ( john duncan sir )))).
• Adding a wildcard symbol may retrieve word variants: (("a duncan smith") or ((("jon duncan sir") OR ("john duncan sir"))))*.