After his studies at Oxford, he returned to New Zealand, becoming the coach of the Wellington NPC team in 1993 and 1994 and also a media commentator. A National Party member, he sought the party's nomination for the 1992 Tamaki by-election, losing to Clem Simich. Kirk was also a staffer for Prime Minister Jim Bolger, and worked as a management consultant at McKinsey & Company. Later he was employed by Fletcher Challenge, then New Zealand's largest company, and one of its successors, Fletcher Energy.