He replaces Karen Chester, who is based in Sydney. She is leaving the firm to become commissioner of the Productivity Commission, the Australian government's independent research and advisory body on economic, environmental and social issues.Mr. Buscombe, a principal who was infrastructure leader for Europe, the Middle East and Africa, is based in London. The firm has yet to announce a successor to that position.Mr. Buscombe developed most of its career at Access Capital Advisers, where he became Partner and Head of UK & Europe before leaving the firm and join Mercer Investment Consulting. He managed European investment origination and asset management across infrastructure, private equity and credit on behalf of institutional investors.Mercer is an American global human resource and related financial services consulting firm, headquartered in New York City.