David Tone Dillon was born in Richmond, Victoria, and was a nephew of the Hon. Patrick Perkins. He received his education in Melbourne, and for several years he was engaged in the brewing industry in Toowoomba while studying for the legal profession. He succeeded in passing the various examinations and was admitted on 17 July 1900.
He was elected Mayor of Dalby Town Council in 1902, and while living in Dalby, entered into journalism and established the Dalby "Leader".
While in Dalby he contested the parliamentary seat with the Hon. J. T. Bell, who was the sitting member of the district, but was defeated by a small majority. He later moved to Brisbane, and commenced practice as a barrister.
David Dillon was a son-in-law of former Mayor, Owen McCarthy.