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David Millar, a Scottish civil servant, made significant contributions to three parliaments. He served as Clerk of the Scottish Parliament from 1999 to 2011, Clerk of the House of Commons from 2011 to 2014, and Clerk of the Scottish Parliament again from 2014 to 2019. In these roles, he played a crucial role in the functioning of the parliaments, providing expert advice and guidance on parliamentary procedure and practice.