Mackenzie was a non-executive director of Centrica from 2005 until 2013.
Mackenzie is a trustee with think tank Demos (where he was Chairman of the Board of Trustees between 2005 to 2007). He is also Group Executive and Chief Executive Non Ferrous at BHP Billiton (since 2008) and Chief Executive Diamonds and Minerals with Rio Tinto plc (since 2004). He previously served 22 years with BP plc (in a variety of senior technical and engineering positions before becoming Group Vice President of BP Petrochemicals). Mackenzie's basic salary for 2007 was £58,000. He also holds 21,000 shares in Centrica as at December 2007.