Cumnock was formerly known as the former Liddell State Coal Mine - a long established underground mine which had operated since the early 1950s. The mine was purchased from the Electricity Commission in 1991. Initial underground mining was carried out using longwall methods within CL 378. However, between 1993 and 1994, the company also extracted coal using open cut methods. Open cut mining recommenced within Stage 3 in November 2002, whilst underground mining ceased in September 2003. Xstrata Coal acquired 100% of Cumnock Coal via its subsidiary Helios Australia Pty Limited, after entering into a Merger Implementation Agreement (“MIA”) to acquire remaining shares of Cumnock Coal for a total of approximately A$23 million in 2007.