Mr Smith joined the asset manager as head of UK equity research in September, having previously been part of Liberum Capital’s equities sales team.
He previously worked as head of UK equities at Neptune, and as a director in the UK large cap team at Schroders.
Mr Harrison will continue to manage the £911m UK Equity Alpha Income fund and other core alpha portfolios, as well as working on Mr Smith’s fund. He will also remain head of equities, Europe.
A Columbia Threadneedle spokesperson said: “We believe that Jeremy’s strong track record and extensive experience will continue to deliver outstanding performance for our clients. As head of equities, Europe, Leigh Harrison will continue to be actively involved in the strategy.”