Iain was born in Glasgow in 1972 and grew up in Hamilton, where his parents still live. He went to primary school in Hamilton and then attended Hutchesons’ Grammar School in Glasgow. After graduating from Exeter University, he worked as an accountant in Milton Keynes before moving to Edinburgh to become Head of Research at the Scottish Conservative & Unionist Party’s HQ. He was also an adviser to the Conservative front bench during the passage of the Scotland Act in 1998.
Iain contested the Rutherglen constituency in the first Scottish Parliamentary elections and has been the MP for Milton Keynes South since 2010. In Parliament, he was a long-standing member of the Transport Select Committee and chaired the All Party Parliamentary Group on Smart Cities. He was also Parliamentary Private Secretary to a number of Cabinet Ministers, including the Secretary of State for Scotland during the passage of the 2016 Scotland Act, which significantly increased the powers of the Scottish Parliament.
In 2018 he was appointed as a Government Whip, serving as the Scotland Office Whip, and in June 2020 he was appointed by the Prime Minister to his role as Parliamentary Under Secretary of State for Scotland.