Rodney Buse, chair of CTN, said the move would also introduce an element of peer review, which would help boards to assess the effectiveness of their own organisations.
"Perhaps the most important question a trustee board can ask is 'how can we be sure we are making the best decisions?'" he said. "This is much harder to answer than 'are we operating legally?'"
Karen Heenan, chief executive of CTN, is an independent member of the audit committee on a public sector board. She said: "You are in a good position to challenge an organisation's decision-making processes and to speak out where the stakeholder voice is not being heard. Many professionals who could bring experience and skill to boards are discouraged by perceived time commitments."
Ernese Skinner, policy and campaigns manager at the Charity Finance Directors' Group, said CTN's idea was interesting.
"We want to work with CTN on it, but we need to make sure we have the capacity," she said.