De Leybourne's claim can be framed precisely because English government recorded offices and powers in writing. During the Civil War, which also amounted to a revolution, Parliament relied on letters and precedents to justify its authority, giving it a reason to preserve records that might otherwise have been destroyed. The surviving archive is uneven: the Blitz and later floods damaged some holdings, and recent files can be less complete than records centuries older. The evidence still leaves the spelling of de Leybourne's name and exact appointment date uncertain, but it supports confidence that he held the office.
Notable Point · 4:38-6:24
Why England's admiralty records survived political upheaval
England's legalistic political culture preserved much of the documentary trail behind de Leybourne's office, although war damage and later floods left survival uneven.