Warren is a Fellow of the Institute of Chartered Accountants in England and Wales (ICAEW). He has degrees in law from Bristol University and mathematics from the Open University. He qualified as a chartered accountant with KPMG in 1990, and has been with Defries Weiss since 1995. He became a principal in 1996.
With a strong background in audit, Warren now specialises in tax planning for individuals and family businesses. He has a wide experience of representing clients in HMRC enquiries, and his main areas of expertise are in income tax and corporation tax.
Outside work, Warren is a magistrate and a keen musician.