Colraine, who has been a non-executive director of the business since 2018, succeeds Jane Barker.
The firm said he has “extensive experience” as a non-executive director, including as chair of Hastings Group Holdings plc and the Compre Group, as well as chairing the Audit and Risk Committee of the Wealth Management Division of Schroders.
He has also held many senior roles in the insurance sector including CFO of AIG Europe Ltd from 2010-2014, which followed his time as COO of AIG UK Ltd and non-executive director and chairman of the Audit Committee between 2007 and 2009.
Prior to AIG Europe, Colraine worked for Willis Group Holdings Inc. for nearly 20 years, from 1988-2007, where he held several senior leadership positions including CFO, vice chairman, and Co-COO.
Chris Lay, CEO, Marsh UK & Ireland, said: “Tom has made a significant contribution to the business since joining the board of directors in September 2018. His extensive expertise and insight of our industry and the regulatory environment will be invaluable as we continue to support our clients and colleagues, and expand our business across the UK and Ireland.
“On behalf of the board, I would like to extend our thanks to Jane for her tremendous leadership, wisdom, guidance and support over the past 10 years, both as chairman and as a non-executive director.”
Colraine added: “Since joining the board, I’ve been impressed by how Marsh continually strives to deliver ground-breaking solutions that help clients of all sizes and sectors mitigate risk and continue to thrive.
“This is especially evidenced by the support offered to clients, colleagues, and communities during the Covid-19 pandemic. I look forward to working with the leadership team as we continue to nurture our talent and develop the UK and Ireland business.”