which airlines did he work for after his training?
Queensland and Northern Territory Aerial Services (Qantas), Trans Australia Airlines (TAA)
Lester Brain
Lester Joseph Brain, AO, AFC (27 February 1903 – 30 June 1980) was a pioneer Australian aviator and airline executive. Born in New South Wales, he trained with the Royal Australian Air Force (RAAF) before joining Queensland and Northern Territory Aerial Services (Qantas) as a pilot in 1924. He was awarded the Air Force Cross in 1929, after locating the lost aircraft "Kookaburra" in northern Australia. Having risen to Chief Pilot at Qantas by 1930, he was appointed Flying Operations Manager in 1938. As a member of the RAAF reserve, Brain coordinated his airline's support for the Australian military during World War II. He earned a King's Commendation for his rescue efforts during an air raid on Broome, Western Australia, in 1942, and was promoted to wing commander in 1944.

Seeing little prospect for advancement at Qantas once the war had ended, Brain left to join the fledgling government-owned domestic carrier Trans Australia Airlines (TAA) in June 1946. 
who was lester brain? Australian aviator and airline executive where was he born? Forbes, New South Wales, Australia which school did he pass out from? Sydney Grammar School at which place did he complete his aviation training at? Royal Australian Air Force (RAAF).
wiki:136987
Lester Brain [SEP] Introduction
Lester Joseph Brain, AO, AFC (27 February 1903 – 30 June 1980) was a pioneer Australian aviator and airline executive. Born in New South Wales, he trained with the Royal Australian Air Force (RAAF) before joining Queensland and Northern Territory Aerial Services (Qantas) as a pilot in 1924. He was awarded the Air Force Cross in 1929, after locating the lost aircraft "Kookaburra" in northern Australia. Having risen to Chief Pilot at Qantas by 1930, he was appointed Flying Operations Manager in 1938. As a member of the RAAF reserve, Brain coordinated his airline's support for the Australian military during World War II.