He was born on 25 October 1847 at St Kitts in the West Indies, and educated at a private school at Melksham, Wiltshire, England. His family had been resident in the West Indies since 1635, primarily involved in administration of the Leeward Islands and in sugar plantations. Burt's great-great-great-uncle, William Mathew Burt, was Governor-General (1776–1781) of the Leeward Islands during the American War of Independence.
He served as an articled clerk to George Frederick Stone, and was admitted to the Bar in 1870. In 1876, Burt went into partnership with Edward Albert Stone (George Frederick’s son), in the firm "Stone and Burt".
He was offered a knighthood in 1901, Knight Commander of St Michael and St George (KCMG), but declined it. He also declined several invitations to join the bench of the Supreme Court, including the position of Chief Justice at the request of Premier George Leake in 1901.
In 1874 Burt accepted a nominated membership of the Western Australian Legislative Council. In 1879 he relinquished that nominee membership, and in the general election of 1880 was elected unopposed for the district of Murray and Williams.
In March 1886 Burt resigned from his seat on the Legislative Council to accept the position of Acting Attorney-General after the sudden resignation of the incumbent Alfred Hensman. Burt remained as Attorney-General until December 1886.
In May 1888 Burt contested a by-election for the Perth seat of the Legislative Council, but lost to John Horgan. In July of that year, he was elected to the North Province seat of the Legislative Council. When Western Australia gained self-government in 1890, he was elected unopposed as the inaugural Legislative Assembly member for Ashburton, and held that seat until he retired from politics in 1900. During this time he was Attorney General (1890–1897), was Acting Premier when the leader, Sir John Forrest, was absent from the State, and was responsible for the creation of the Western Australian Agent-General's office in London and acted in that position from 1891-1892. Sir Malcolm Fraser KCMG took over in 1892 as the official Agent General for Western Australia. Burt was also a member of the Executive Council (1890–1901). He also served as "Minister without portfolio" from 1897-1900.
In 1877 Burt formed a syndicate with John, Alexander and David Forrest and took up a 590,000-acre (240,000 ha) lease of land on the Ashburton River. This lease became known as Minderoo Station. He was also owner or part-owner of other properties, including Kadji Kadji, Brick House (near Carnarvon), Yinnetharra,[Note 1] Red Hill, Gifford Creek and Minne Creek. The syndicate was dissolved in later years, with the families taking separate ownership of the properties.
In 1917 Burt and his wife funded and donated to the Church the Burt Memorial Hall on St Georges Terrace, as a memorial to their two sons killed during World War I. Initially it was to commemorate their son Theodore, who died in 1917, but a second son, Francis, was killed in 1918 before the construction was complete.
- The Australian Dictionary of Biography and Biographical Register of Members of the Parliament of Western Australia spell the station name as "Yinniethana", apparently incorrectly.
- De Garis, B. K.; Stannage, Tom. "Burt, Septimus (1847–1919)". Australian Dictionary of Biography. National Centre of Biography, Australian National University. Retrieved 2011-07-24.
- Muir, Alison & Dinee (1982). Forrest Family, Pioneers of Western Australia, 1842-1982. J.R. Muir & Son. pp. 101, 105–106. ISBN 0-9592883-0-9.
- Burt Family Papers and Personal Notebook, J S Battye Library, Perth
- "Antigua and Barbuda". World Statesmen.org. Retrieved 2011-08-23.
- B. Schemmel. "Countries An-Az: Antigua and Barbuda". rulers.org. Retrieved 2011-08-23.
- Carribeana, Colonel H W Pook
- The House of Commons: 1660 - 1690 ; 3, Members M - Y, Stanley T. Bindoff, John S. Roskell, Lewis Namier, Romney Sedgwick, David Hayton, Eveline Cruickshanks, R. G. Thorne, P. W. Hasler
- Black, David; Bolton, Geoffrey (1990). Biographical Register of Members of the Parliament of Western Australia. One, 1870-1930. p. 41. ISBN 0-7316-9782-0.
- Bolton, Geoffrey; Byrne, Geraldine (2005). May it please Your Honour : a history of the Supreme Court of Western Australia 1861-2005. ISBN 0-9590067-7-X.
- "Burt, Septimus (1847–1919)". Obituaries Australia. National Centre of Biography, Australian National University. Retrieved 2011-07-24.
- "Death Of Mr. Septimus Burt, K.C.". Western Mail (Perth, WA : 1885 - 1954) (Perth, WA: National Library of Australia). 16 May 1919. p. 30. Retrieved 24 July 2011.
- "Summary Of Record Information - Septimus Burt". Metropolitan Cemeteries Board, Government of Western Australia. Retrieved 2011-07-23.
- "Hensman, Alfred Peach (1834–1902)". Australian Dictionary of Biography. National Centre of Biography, Australian National University. Retrieved 2011-07-24.
- Burt-Forrest Correspondence, J S Battye Library, Perth
- Erickson, Rica (1987). The Bicentennial Dictionary of Western Australians pre-1829 - 1888. I, A-C. University of Western Australia Press. p. 409. ISBN 0-85564-270-X.
- McDonald, Rhonda (1991). Winning the Gascoyne. Hesperian Press. p. 88. ISBN 0-85905-158-7.
- Hare-Naylor genealogical records
- Register of Heritage Places - Assessment Documentation: Burt Memorial Hall, Heritage Council of Western Australia, 2004-02-20, retrieved 2011-07-25
- Carnarvon Club History