	Poppelwell was the tenth of twelve children of his parents, William Poppelwell, a Scottish mariner turned farmer, and his wife, Catherine Robertson McLachlan. His family's house was known for their hospitality, as well as being a centre for local Catholics. He attended the Christian Brothers' Boys' School in Dunedin, and was awarded the Bishop Moran's Scholarship in 1878. He later became a law clerk in the office of Donald Reid in Milton. He was also appointed lieutenant in the Bruce Rifle Volunteers in 1887. From 1889 to 1891 he studied law at the University of Otago, and once he was admitted as a lawyer, he moved to Gore to establish a practice there.