Australian academic Bob Catley wrote a book titled "Waltzing with Matilda: should New Zealand join Australia?", a book arguing that New Zealand should become one with Australia, which was described by New Zealand political commentator Colin James as "a book for Australians". In December 2006, an Australian Federal Parliamentary Committee recommended that Australia and New Zealand pursue a full union, or at least adopt a common ANZ currency and more common markets. The Committee found that "while Australia and New Zealand are of course two sovereign nations, it seems... that the strong ties between the two countries – the economic, cultural, migration, defence, governmental and people-to-people linkages – suggest that an even closer relationship, including the possibility of union, is both desirable and realistic." This was despite the Australian Treasurer Peter Costello and New Zealand Minister of Finance Michael Cullen saying that a common currency was "not on the agenda".