The Advisory Committee on Advertising (ACA) told Cabinet Office officials at a meeting last week that they remain committed to their voluntary work, but only if their views are taken more seriously within Whitehall.
The acid test will come in the next few months, when ACA is expected to assess the effectiveness of the Department for Transport's (DfT's) £20m adspend following its breakaway from COI Communications.
Members of ACA, who include Shell global brand chief Raoul Pinnell, Sainsbury's assistant managing director Sara Weller and Britvic category director Andrew Marsden, were furious earlier this year when the Cabinet Office failed to prevent a split between the DfT and the COI. ACA chairman Derek Dear resigned over the issue and has now been replaced by UKTV chief executive Dick Emery.
The Committee has subsequently been promised a bigger role, with the ability to pre-audit any government departments thinking of following the DfT lead.
A Cabinet Office spokesman said: "Ministers have deliberately raised the status and reach of ACA because they value its recommendations and advice."