Charles (UK) is an Excel expert who specializes in performance — he is a world leader at making Excel go faster. One of his specialties is making your VBA UDFs (User Defined Functions) more efficient. After leaving IBM in 1996, he founded a Microsoft Office consultancy and software development company - Decision Models. His particular interest areas are: Excel Calculation performance, VBA UDFs & VBA Performance, Excel JS API, Large Excel model,  Excel Defined Names, Excel as frontend to Relational Databases, C++ XLLs.

Charles is co-author with Jan Karel Pieterse of Name Manager, a widely-used utility for managing Excel defined names, and author of FastExcel, a commercial product to help optimize Excel calculation speed.

He is the developer of Lambda Explorer, the FastExcel Addin Family, and others.

Microsoft MVP for Excel since 2009.

The topic of his lecture at the conference is: "Developing and Debugging Lambdas and Lets"

And the topic of his Мasterclass:
Excel Hackaton: "Developing Excel VBA Addins: the LET Wizard addin"