The appointment of BNZ chief executive Andrew Thorburn to National Australia Bank's top job may have surprised Australian banking analysts, but it was not such a shock for those in New Zealand who have worked with Thorburn and seen how many NZ bank chief executives graduate to top jobs in Australia.Thorburn, 48, is following a well-trodden path, and not just within NAB, where he will be the second CEO in a row to be recruited from the top job at its NZ unit.  He has also travelled a similar path to those now leading Commonwealth Bank. Ralph Norris, who led Commonwealth Bank's ASB for all of the time Thorburn was learning the ropes as a regional manager at ASB in Auckland through the late 1980s and 1990s, went on to infuse CBA with many of the same disciplines and culture that worked for him at ASB, particularly around customer satisfaction, marketing and cost control. Although born in Melbourne and widely seen as an Australian banker, Thorburn completed his commerce degree at Auckland University and has spent most of his banking career in NZ, apart from stints working for Commonwealth Bank, St George and then NAB through the early 2000s.A fan of the Aussie Rules team Essendon, he has also warmed to the All Blacks and encouraged BNZ to become the main sponsor of all of New Zealand's Super 14 Rugby teams. This is said to be the most effective corporate sponsorship in NZ sport. People who have worked with, and under, Thorburn in New Zealand have described his style to Banking Day as "inclusive, approachable, energetic and engaging".Former colleagues cited his championing of gender and racial diversity within BNZ. The United Nations awarded Thorburn a "Benchmarking for Change" honour last year after he embedded gender balance targets into performance plans.  Half of BNZ's executive team are women.Thorburn is also unusual in NZ executive ranks as having learned enough Maori to speak for ceremonial purposes during official welcomes to tribal groups, who control over NZ$40 billion of assets.Banking industry figures in New Zealand pointed beyond Thorburn's 'soft' skills to a sharp improvement in the financial and customer satisfaction performance of BNZ since 2008.  They said he had focused on driving down BNZ's cost income ratio and driving up customer satisfaction during his time in charge.BNZ's annual cash profits improved 41 per cent to NZ$788 million since 2008, while its cost to income ratio fell from 47.8 per cent to 40.3 per cent over the same period. BNZ also overtook ASB in the Roy Morgan customer satisfaction in January to become top ranked among the big four Australian-owned banks in New Zealand, after being the lowest rated among its peers in late 2008. "Those guys at NAB might get a bit of a shock. He's now running a pretty lean operation at BNZ," said one executive.NAB's cost income ratio was 42.6 per cent last year.