Background
Brentnall was born on 30 December 1846 at Escomb, County Durham, England, son of Joseph Edmund Brentnall, a chemist, and his wife Mary Ann, née Strutt.
Brentnall was born on 30 December 1846 at Escomb, County Durham, England, son of Joseph Edmund Brentnall, a chemist, and his wife Mary Ann, née Strutt.
The family lived at Eston, Yorkshire, and Brentnall was educated at private schools at Great Ayton and Darlington.
He was the nephew of Thomas Brentnall, the 9th Mayor of Middlesbrough (1862). He matriculated at the University of Durham but on departing education he joined the Middlesbrough branch of the National Provincial Bank of England. After working briefly with the London Bank of Australia Brentnall established himself as a public accountant, and acquired two existing practices which brought him an immediate clientele of top Australian businessmen and pastoralists.
Despite an early financial setback, owing to a defaulting partner whose liabilities Brentnall fully repaid, he developed a successful business which evolved with several names, Brentnall & Riley, Brentnall, Norton & Company, and Brentnall, Mewton & Butler.
From 1880 he lived at Newnham, Caroline Street, in South Yarra. In 1886 he helped to found the Incorporated Institute of Accountants, Victoria, and became president of the institute in 1898.
In 1907 he was first president of the Australasian Corporation of Public Accountants and in 1928, when a royal charter was granted, he became first president of the Institute of Chartered Accountants in Australia. Later in life he served many years at the Victorian Companies Auditors" Board as examiner, director and chairman.
Brentnall was a keen golfer. As early as 1874 he had been a member of the Royal Musselburgh Club in Scotland.