Frederick George Ewington was born in Barnet, Hertfordshire, England, on 27 May 1844, the son of William Ewington, a labourer, and his wife, Jane Briers. Frederick was educated at nearby High Barnet. He arrived at Auckland, New Zealand, on 20 October 1862 on board the Indian Empire. Ewington may have come out as a farm labourer, but he joined the military forces in Taranaki almost at once. He served with Harry Atkinson's irregular forces and then in Waikato as Lieutenant General Duncan Cameron's orderly. He was awarded the New Zealand War Medal for his part in the storming of Rangiriri in 1863. On 22 December 1864 he married Mary Catherine Phelan at Auckland.
With the Waikato war concluded Ewington returned to Auckland and in 1866 commenced business as a land and estate agent under the name of Ewington and Baker. Auckland had begun the process of expansion which was to make it New Zealand's largest urban area, and Ewington and Baker's success lay in helping to facilitate that development. By 1882 Ewington himself held a total of 277 acres in Eden, Manukau and Waitemata counties. His sense of prudence led him to avoid the worst excesses of the speculative boom of the 1870s; unlike many of his contemporaries, he was not swept away by the subsequent crash in the 1880s. In fact, he appears to have been a sturdy pillar of an otherwise shaky Auckland business community; he was a member of the Auckland Chamber of Commerce and frequently served as an assessor on the magisterial Bench in law and property cases requiring expert knowledge.
It was for philanthropic work, however, that Ewington became best known. Described as 'one of the great unpaid', he was a member of the Anglican Holy Trinity Parish in Devonport, a lay reader, a long-time Sunday school teacher, and a member of the diocesan synod. As a member of the Young Men's Christian Association he was tireless in helping new immigrants into jobs. Ewington was one of the original founders of the Auckland Prisoners' Aid Society, the Women's Home, the Jubilee Institute for the Blind, the Veterans' Home and the Auckland Sailors' Home. From 1886 he was an official visitor to the Auckland Lunatic Asylum (later the Auckland Mental Hospital), and for over 30 years was honorary secretary of the Auckland Ladies' Benevolent Society. He served on the Prisons Board, was an official visitor of prisons and a justice of the peace. For two years he was chairman of the Auckland North Licensing Committee and served on various road boards and school committees. He was also president of the North Shore Rowing Club.
Ewington was known as a lecturer and writer on historical subjects and on social and labour questions. A founder of the National Association of New Zealand in 1891, he published pamphlets advocating conservative political ideals. He blamed the 1890 maritime strikers for prolonging the depression, and was strongly opposed to the Liberal government which he accused of purchasing popularity by class legislation. 'There is too much legislation; there are too many experiments, too many bids for popularity and office'. He attacked 'state socialism' as an obstacle to enterprise, and claimed that the government's social legislation hindered self-reliance. In the Liberals' turbulent populist democracy, he wrote, 'the wisest and best men in the Colony get defeated by noisy, self-assertive carpet-baggers, who only take to politics for a living when all else fails.' Ewington looked for a stable, quiet and prosperous New Zealand governed by true religion, sound political economy, and a government which strove to 'imbue men with a national instead of a mere class sentiment'. His political writings thus complemented his activities as war hero, businessman and philanthropist.
Frederick George Ewington died on 27 June 1922, at his home at Cheltenham Beach, Devonport. His wife, Mary, had died on 29 April 1920. He was survived by seven daughters and three sons. Three other children had predeceased him, including a son, F. W. Ewington, killed at Gallipoli.