Ian Stewart was elected a Fellow of the British Academy for his outstanding contribution to British numismatics. His areas of interest were the Scottish coinage, Anglo-Saxon and later medieval English coins. He published extensively, The Scottish Coinage and English Coins 1180–1551 being standard works. Yet he never held an academic post. His collections of English and Scottish coins were outstanding. Stewart was a banker by profession but had a second career in politics, holding several ministerial posts in the 1980s. He was knighted and subsequently raised to the peerage as Lord Stewartby in 1992.