National Australia Bank must be hoping that extensive experience in Australia's small business banking market provides the right grounding to make an impact on Asia's banking scene.Yesterday, NAB confirmed that Daryl Johnson will take over as head of NAB's business in Asia, based in Singapore.Johnson replaces Spiro Pappas, who will return to Australia.At present, Johnson is executive general manager for NAB's business bank in Australia. He used run NAB's corporate business before this.He crossed to NAB from ANZ's business banking division in 2009. Pappas will take over as head of institutional banking and will report to Joseph Healy, NAB's group executive for business banking.Pappas replaces David Hornery, who is shifting to become NAB's executive general manager of corporate and specialised business, including agribusiness and health.Hornery will take on an extra role as chair of NAB's Australia in Asia council.