Blanc told the audience it was an "excuse" to say a company could not focus on diversity because there were so many other things going on.
In words echoed by Hinton later on in the panel session, Blanc added: "Diversity isn't just a project that you start and finish; it is part of what your business is, and either you believe in it or you don't."
Fellow keynote speaker Chris Hayward, policy chairman at City of London Corporation, has long been a dedicated supporter of HM Treasury's Women in Finance charter.
He said: "Financial services in the City of London must be a place where everyone belongs. That is particularly true in leadership.
"We need a culture that welcomes everyone. If we want to continue to be successful, we need the best people - and that can only be achieved by welcoming all diversity of leadership.
"Female leadership is crucial to providing role models for the next generation, helping to build an equitable inclusive talent pipeline."
