Dein was born at Lucknow, New South Wales and was educated at Shadforth Public School.

He left school at 14 and worked as a gold miner and on a dairy farm before training as a teacher in 1907.

He taught at Hadsonville and Hanover, Neville, Dubbo and Narromine before moving to Dulwich Hill in Sydney in 1921.

He was heavily involved in local sporting circles, playing both first-grade cricket and tennis for Marrickville.

[1] In 1929, he contested the Division of Lang in the Australian House of Representatives as a Nationalist, but was unsuccessful.