Deverell, Averill Katherine Statter (1893–1979), barrister, was born 2 January 1893 in Greystones, Co. Wicklow, the only daughter (she had a twin brother) of William Deverell of Ellesmere, Greystones, clerk of the crown and peace, and his wife Ada Kate Statter Carr. As a teenager she learnt how to drive – her father was one of the first men to own a motor car in Greystones. She felt obliged to make a contribution to the war effort, and once she had secured her father's permission she contacted the Queen Alexandra first aid nursing yeomanry, offering her services as a driver. When she enlisted she was required to take a driving test at the Royal Automobile Club in London, which she successfully passed. Then she was asked to re-assemble a dismantled engine, which she failed miserably to do. But this requirement was abolished six months later, and she drove an ambulance for the rest of the war.
When Deverell returned from the war, she entered TCD to study law, and graduated as a junior moderator and LLB. The Sex Disqualification (Removal) Act of 1919 removed the legal bar to women being appointed to public office, and women in both Britain and Ireland began to apply to enter the legal profession almost immediately. In January 1920 the King's Inns benchers passed a resolution that stated ‘that women shall be admitted on precisely the same terms as men’; in the spring of 1920, Deverell and Frances Christian Kyle (1894–1958) were the first women to be admitted to the King's Inns. On 2 November 1921 she was called to the Irish bar, thus making legal history in Ireland and around the world; she and Kyle were the first women in Britain and Ireland to be admitted to the bar. The Irish Law Times noted that the call was of ‘great and unusual interest to the profession and to the public, as ladies were called for the first time in the history of the Irish Bar’ (5 Nov. 1921, 272). They made headlines not only in Ireland but also in the New York Times and the Times of India. Photographs of both women in the traditional wig and gown accompanied the headlines. It was an auspicious occasion for political reasons, as it was also the first call of a divided Irish bar, following the Government of Ireland Act 1920 which created separate jurisdictions for north and south. Her twin brother, Captain William Deverell, was called to the bar on the same day. Although she and Kyle were called to the bar simultaneously, Deverell was the first woman to practise at the bar in Ireland. She was called to the northern bar in 1922.
Following qualification Deverell established a considerable chancery practice and was an active barrister until her retirement forty years later. She remained an active campaigner on behalf of women in the legal profession. When the women's dressing room in the Law Library of Ireland was moved in the 1930s, she organised fellow women barristers in a campaign to get their room back. Then ‘Lady Barristers’ appeared on the door of the room, and she insisted that this should be replaced with ‘Women Barristers’. She died 17 February 1979 in her childhood home in Greystones, aged eighty-eight. Her portrait now hangs in the Law Library.