Perhaps you should try some spelling variations:
brown duncan » brown dunstan, brian duncan, john duncan
ian duncan » brian duncan, a duncan, innes duncan
jon duncan » john duncan, j duncan, colin duncan
duncan sir » duncan i, 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: (( ((ian duncan) OR (jon duncan)) smith ) OR ( brown duncan sir )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((ian duncan) OR (jon duncan)) smith ) or ( brown duncan sir ))".
• Adding a wildcard symbol may retrieve word variants: (( ((ian duncan) OR (jon duncan)) smith ) or ( brown duncan sir ))*.