Vicars was born on 27 July 1862 in
Leamington Spa, Warwickshire, and was the youngest child of Colonel William Henry Vicars of the
61st Regiment of Foot and his wife Jane (originally Gun-Cunninghame). This was his mother's second marriage, the first being to Pierce O'Mahony by whom she had two sons. Arthur was very attached to his Irish half-brothers and spent much time at their residences. On completing his education at
Magdalen College School, Oxford and
Bromsgrove School he moved permanently to Ireland. He quickly developed an expertise in genealogical and heraldic matters and made several attempts to be employed by the Irish heraldic administration of
Ulster King of Arms, even offering to work for no pay. In 1891, he was one of the founder members of the
County Kildare Archaeological Society, and remained its honorary secretary until his death. He first attempted to find a post in the Office of Arms when, in 1892, he applied unsuccessfully for the post of
Athlone Pursuivant on the death of the incumbent, Bernard Louis Burke. In a letter dated 2 October 1892 Vicars's half-brother Peirce Mahony wrote that Sir
Bernard Burke,
Ulster King of Arms, was dying and urged him: "You should move at once." Burke died in December 1892, and Vicars was appointed to the office by
letters patent dated 2 February 1893. In 1896 Arthur Vicars was knighted, in 1900 he was appointed Commander of the
Royal Victorian Order (CVO) and in 1903 he was elevated to Knight Commander of the order (KCVO). He was a fellow of the
Society of Antiquaries and a trustee of the
National Library of Ireland. In 1897, Vicars published
An Index to the Prerogative Wills of Ireland 1536 -1810, a listing of all persons in wills proved in that period. This work became very valuable to genealogists after the destruction of the source material for the book in 1922 when the Public Record Office at the
Four Courts was destroyed at the start of the
Irish Civil War. ==Theft of the Irish Crown Jewels==