First names before 1558 have been normalized, where appropriate, as generally also in both C. L. Kingsford’s 1908 edition of John Stow’s A Survey of London and A. B. Beaven’s The Aldermen of the City of London (1908--13). (See Sources, on the site menu bar, for this database’s use of these reference works). The surname spellings used for Beaven's mayors and aldermanic sheriffs, to 1912, are from Beaven's chronological listings and the text immediately preceding them in volume 1, and for the non-aldermanic sheriffs he mentions, from his index. (For aldermanic and non-aldermanic status, see Sources.) For names not in Beaven, to 1602 the main surname spellings in Kingsford's edition of Stow are followed, with “Fitz” reproduced as “fitz-” (as in Beaven) except where footnoted otherwise, S. (for “Saint”) as St., and “filius” as “fitz-”. (The modern "son of", for "fitz-", appears only in a few footnotes.) For names not in either Beaven or Kingsford's Stow, the spellings are from the indexes of the relevant volumes of Reginald R. Sharpe’s 11-volume Calendar of Letter-Books Preserved Among the Archives of the Corporation of the City of London at the Guildhall, A–L (1899–1912), to 1497, and otherwise from manuscript sources. From 1912, spellings are from John Chalstrey's Aldermen of the City of London 1900--2010 (2011) and from manuscript and online sources.
If you are unsuccessful in a name search of the database, try variant spellings: e.g., Broun for Brown, Austyn for Austin; or search a range of years instead. The search program contains some variant spellings, and some alternate names, but in general cannot do fuzzy searches.