KEITH Skeoch, chief executive of Standard Life Investments, has warned British companies should not follow the American model of only allowing two executives on their boards.
There has been a move towards this approach due to concerns that the board dominance of powerful executives had contributed to the banking crisis.
At RBS and Lloyds Banking Group, the chief executives and finance directors are now the only executives on the board.
But Mr Skeoch said: "I'd hate to see us go down the US model where it's only the chief executive and CFO. It is incredibly important to get executive representation on the board."
The funds chief told the Association of British Insurers' investment conference that a unitary board of executives and non-executives assisted transmission of culture within an organisation.
Non-executives, particularly at the banks, have been criticised for not devoting enough time to their roles in the past.
"I think the rewards associated with giving up your time, and the enhanced level of risk and exposure of non-executives take, will go up," Mr Skeoch said.
But Lesley Knox, former chairman of Dundee-based Alliance Trust and non-executive director at Scottish Gas-owner Centrica, disputed this.
"I do not do my non-executive directorships, and people I know do not do them, for money," she said.
"The real risk for any non-executive is your reputation being absolutely trashed.
"There is no amount of money that could pay you for your reputation."