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

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 ("a duncan sarah"))) OR ((("ian duncan sir") OR ("john duncan sir")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"a duncan smith\") OR (\"a duncan sarah\"))) or (((\"ian duncan sir\") or (\"john duncan sir\"))))".
• Removing quotes may allow a broader search: (((( a duncan smith ) OR ( a duncan sarah ))) or ((( ian duncan sir ) or ( john duncan sir )))).
• Adding a wildcard symbol may retrieve word variants: (((("a duncan smith") OR ("a duncan sarah"))) or ((("ian duncan sir") or ("john duncan sir"))))*.