Gary has held various roles in Trade Finance Operations, Trade Product Management and Trade Sales with Midland Bank (then acquired by HSBC), Citibank and ABN Amro.

He was a Technical Adviser and Senior Technical Adviser to the International Chamber of Commerce, Banking Commission from November 1996 to July 2013. From August 2016 to date, editor and reviewer/assessor of responses to enquiries made by nominated technical advisers.

Chair of the ICC Task Force (Working Group) for the development of the ISP98 and the strategy for a revision of UCP500. Chair of the working group that revised the UCP500 and updated the ISBP (Publication 681), URR525 and eUCP (2003-2007). Chair of the drafting groups for the revision of ISBP (Publication 745) and the development of rules for the BPO - Bank Payment Obligation- (URBPO).

Co-chair of the drafting group for the revisions of eUCP and the drafting of eURC. Adviser for the drafting of the URDTT (Uniform Rules for Digital Trade Transactions).