Robert Woodward "Bob" Hathaway was 'jure uxoris' seigneur of Sark from 1929 until his death. An American by birth, his rule spanned the reigns of four overlords: George V, Edward VIII, George VI and Elizabeth II. Wikipedia*
On the C-SPAN Networks:
Robert Hathaway has one video in the C-SPAN Video Library; the first appearance was a 1991 House Committee.