This interesting and unusual name is of medieval Scottish origin and is locational from a place called Haddo in the former county of Aberdeens, which is now part of the Grampian region. The derivation is from the Middle English 'half', and the Gaelic 'dabhach', a land measure equivalent to four ploughgates. The surname is prevalent in the shires of Kirkcudbright, Ayr and Lanark, and may also be a form of Haddock, a name possibly from Haydock in Lancashire or connected with Haddockstone in Renfrewshire. In the commissariot record of Hamilton and Campsie 1564-1800, one Archibald Haddow in Overgvarter is recorded in 1603, and one Anna Haddo was christened in Metzlick, Aberdeen, on January 26th 1709. The first recorded spelling of the family name is shown to be that of Alanus de Haldawach, which was dated 1382, 'Dictionary of Surnames' - Hank and Hodges, during the reign of King Richard 11, 'Richard of Bordeaux', 1377-1399. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.