Bush joined the New Zealand Police in 1978, working at both CIB and Frontline Policing. As he progressed through the ranks he was appointed to senior roles, including Liaison Officer for South East Asia. This position was held by Bush at the time of the 2004 Boxing Day tsunami. He was the first New Zealand official on the scene of this incident, arriving on Phuket to assist with relief. In the 2006 New Year Honours, he was appointed a Member of the New Zealand Order of Merit (MNZM) for his relief work. He was also awarded the New Zealand Special Service Medal (Asian Tsunami) recognising this work.