It depends on which John Kerr, you are talking about:
Sir John Kerr (governor-general) (1914-1991), Australian
Governor-General
John Kerr, Baron Kerr of Kinlochard (born 1942), British
diplomat
John Kerr (US politician) (c. 1778-1823), Irish-born mayor of
Columbus, Ohio
John Leeds Kerr (1780-1844), U.S. Senator from Maryland
John Kerr (Virginia Congressman) (1782-1842), Virginia
politician
John Kerr, 7th Marquess of Lothian (1794-1841), Scottish
politician and peer
John Bozman Kerr (1809-1878), U.S. Representative from
Maryland
John Kerr, Jr. (congress) (1811-1879), Congressional
Representative and jurist from North Carolina
John Kerr (British politician) (1852-?), UK MP for Preston,
1903-1906
Sir John Henry Kerr (1871-1934), colonial governor in British
India
John H. Kerr (1873-1958), Congressman from North Carolina in the
20th century
John H. Kerr, III (born 1936), North Carolina politician
John Kerr (Nelson politician) (1830-1898), New Zealand (Nelson)
politician
John Kerr (Auckland politician), New Zealand (Auckland)
politician
