"The business has taken the decision to locate our senior team in Melbourne, bringing the team close to our two operating businesses," TPI CEO Bob Boucher said in a statement.
"At the time, Stewart decided that relocating to Melbourne was not the right move for his family and over the past 10 months, we have both tried to make this work. Unfortunately, it has been a compromise for Stewart, his family and the business that is no longer sustainable. So together we have decided that he will step down from the role."
Replacing him is Gill, who had a 26-year career at BHP Billiton in finance, including vice president finance carbon steel, CFO for both stainless steel materials and nickel businesses and global lead risk management and audit.
Since BHP Billiton, Gill has held CFO roles in the mining and energy sectors and was most recently CFO for Inova Resources (formerly Ivanhoe Australia).
"Brendan's reputation for building robust financial process and strong financial management discipline, as well as his team leadership skills were the key reasons that he stood out as the preferred candidate and why I'm looking forward to him joining my team," Boucher said.