Hedley Allen Dunn (27 October 1865 – 5 June 1942) was a South Australian architect, a member of the prominent Dunn family of Mount Barker. His work included the flour mill at Port Adelaide for his father and grandfather in 1886, and the Stock Exchange Building in Grenfell Street, Adelaide, in 1900.
Hedley was born in North Adelaide and was schooled at Prince Alfred College for several years before attending The Leys School, a Methodist boys' school in Cambridge, England with his brother Frederick.
He returned to Australia in 1881 and studied architecture with fellow students Frank H. Counsell and Alfred M. Bonython; examiners included E. Davies and E. J. Woods. He found employment with Ellerker and Kilburn of Melbourne, then Oakden, Addison and Kemp for whom he travelled to Auckland, New Zealand to design a health retreat at the hot springs in Waiwera. He worked for a time in Brisbane, then returned to Adelaide, where in 1886 he opened his own practice in Freeman Street. His major project in this period was a large flour mill at Port Adelaide for his father's family business; brother Alfred Calvert Dunn was engineer. This superseded an earlier mill designed and executed by Wright, Woods & Hamilton.
In September 1887 he was taken on as partner by Edward Davies in Flinders Street Adelaide, dissolved 1888. They produced a prize-winning design for the new Commercial Bank at 25 King William Street. Dunn designed the elaborate blackwood case for the new organ at the Kent Town Methodist Church in 1898, no doubt pro bono. His design for a building for the Royal Bank of Queensland was rejected, but they nevertheless opened a practice in Queen Street, Brisbane in 1890. He married in Queensland in 1893. He returned to Adelaide and opened his own offices in King William Street, working mainly on residences, but was also brought in to design extensions to the Dunn Memorial Church in Mount Barker, no doubt also pro bono.
In 1899 Dunn collaborated with Gilbert Place, Adelaide architect Henry Ernest Fuller on a design for the new YWCA building (not adopted) and the Adelaide Stock Exchange on the McHenry Street corner, for which they won both first and second prizes, and was built in 1901. He was responsible for the new grandstand at Prince Alfred College in 1904.