Before going into politics, Cretney was a shop manager (1977–85) and he was also a businessman in the period 1985–2012. He was, until March 2014,
Minister of Infrastructure in the
Isle of Man Government, and had formerly headed the Departments of
Community, Culture & Leisure,
Trade & Industry, and
Tourism & Leisure. He was a
Member of the House of Keys for the
Manx Labour Party, representing
Douglas South from 1985. He has been a member of the upper house, the
Legislative Council since 2015. In December 2012 and early January 2013 he closed down his two bargain-basement retail outlets having chosen not to renew the leases on either of his premises. He was elected in the
2025 Manx local elections to the
Douglas City Council. ==Governmental positions==