Callen has a unique ability to solve complex commercial issues for clients in a way that makes them feel empowered and better able to make the right decisions. He has established himself as a strategic and commercial advisor for the procurement of major government service arrangements, harnessing a deep appreciation of risk allocation, procurement processes and stakeholder and market engagement to achieve cleint objectives. He has worked on several multi-year engagements and is recognised by his peers for his ability to form long-term partnerships with clients. He is passionate about the transaction environment and considers it a privildge to have opportunities to work with clients in the transport, and health and human services sectors.