John Duffy Director - Audit and Assurance Dublin, City Quay +353 (0)1 408 6922


John joined Grant Thornton in 2015 from a merged firm. John also has significant “Big 4” experience.

John has extensive experience in delivering and coordinating the audits of large domestic and international groups. He has vast experience of working with multinational finance teams and auditing under IFRS, US GAAP and Irish GAAP. He has a history of delivering valuable group reporting on time. John has advised numerous clients that report under IFRS particularly within the manufacturing, retail and distribution sectors.

Sector Experience

He has 20 years’ experience in practice and has a wide range of business experience including not-for-profit, technology, professional services and the more traditional areas of retail, manufacturing and construction.

John has written numerous technical articles for various accounting publications and has also lectured and presented on such topics.

John was also on the board of Sophia Housing for five years to end January 2020, he remains a member of the finance sub-committee.

  • Holds an Honours Degree in mathematics and economics from the University of Sheffield
  • Fellow of Chartered Accountants Ireland (CAI)