This branch left the Main North just to the west of Branxton Station. It serviced the colliery known at various times as Rothbury, Branxton and finally Ayrfield No 3 Colliery. It was with its original name when it was the site of the infamous Rothbury Riot, when striking miners clashed with armed police.
Mining ceased with the closure of the mine on 20/12/1973.
The branch has been taken over by the Hunter Valley Railway Trust, which operates a museum specialising in passenger cars, and has plans to operate a steam service over the line.