In a hiring decision with the potential to put one of its longest running transaction banking contracts under the spotlight, Westpac has announced the appointment of a cabinet minister as head of its private bank in New Zealand.Simon Power, 41, will take up the post from January. In February, Power announced his decision not to stand for Parliament at the general election, which is to be held next month. Power holds three portfolios in the NZ cabinet: Minister of Justice, Minister of Commerce and Minister of Consumer Affairs. He is also the minister responsible for the Law Commission and holds the title of Associate Minister of Finance. In addition, he also serves as Deputy Leader of the House in the New Zealand Parliament for the National Party Government.Power had ministerial responsibility for the formation of the Financial Markets Authority, which replaced the Securities Commission this year.The move of a cabinet minister to a senior executive job with a bank of which he was a regulator is unusual in New Zealand, though not subject to any legal restraint.The private banking operation of Westpac in New Zealand is a niche service, given the population is only four million and the number of genuinely wealthy people in need of sophisticated advice would only number in the thousands.Whatever the true number, it may be in decline.Boston Consulting Group, in a report published in June, said of the outlook for wealth in New Zealand that it had "negative projected growth".Westpac has held the banking contract with New Zealand's central government since 1989. There has been no competitive tender since that time, though the topic has been the subject of some debate over the last year or so.In June, the Government said that it would put the contract out to tender, but this has not yet been done. The dissolution of Parliament is likely later on this week in preparation for the election on November 26.