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Callum Mayor

Managing Director
London, UK

Callum Mayor is a managing director in Milliman’s Business Advisory Practice. He advises boards and executive teams on navigating complex transformation, growth, and integration challenges across insurance and financial services.

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Experience

With over 25 years’ experience, Callum brings deep expertise in strategy‑led transformation, operating model and governance design, and large‑scale organisational change. He works with senior leaders to define direction, make confident decisions, and embed sustainable outcomes, particularly in environments shaped by regulation, cost pressure, and technology‑driven disruption.

Prior to joining Milliman, Callum held senior leadership roles at Wavestone and PEN Partnership and has a strong track record in building and scaling advisory capabilities, including playing a senior role in growing a consulting firm from inception to over £20m in revenue. His advisory work spans post‑merger integration, digital and technology‑enabled transformation, outsourcing strategy, and enterprise cost and performance improvement.

He has led and developed multi‑disciplinary teams through periods of growth and complexity, combining strategic insight with a pragmatic understanding of how organisations execute change. Callum is particularly recognised for his inclusive leadership style and focus on culture, with a consistent record of building high‑performing teams centred on wellbeing, equity, and talent development.