Sir Francis Walsingham-Born: 1530, Scadbury Park, Chislehurst, Kent, England-Died: 6 Apr 1590, Seething Lane, London, Middlesex, England Principal Secretary to Elizabeth I of England from 1573 until 1590, and is popularly remembered as her "spymaster". Elizabeth I. nicknamed him her 'Moor'.
Portrait of "SIR FRANCIS WALSINGHAM" by Houbraken - Antique Print - 1738
Cryptography in the 16th century. A nomenclator combines a substitution cipher with a small code set, as in the famous one shown in Figure 7-6. Mary Queen of Scots and her cohorts used this nomenclator during a plot against Queen Elizabeth I. Thomas Phelippes (cipher secretary to Sir Francis Walsingham, principal secretary to Elizabeth I) used frequency analysis to break it. Phelippes’ success cost Queen Mary her royal head.