Complex sentence: Alfred John Stephenson (1846-1914) had experience as a composing room employee but at "The Queensland Times" became a managing director, a position he held for more than 45 years.
Split into simpler sentences: Alfred John Stephenson (1846-1914) had experience as a composing room employee. However at "The Queensland Times" he became its managing director, a position he held for more than 45 years.