Future reforms to governance could “compound” the problem that UK company boards are bogged down in risk mitigation and compliance monitoring, rather than supporting executives in investing for the long term, a think-tank warns.

The report, conducted by Tomorrow’s Company, says that boards are “weighed down” with 25 years of reforms following a succession of corporate scandals. The answer, it says, is for investors to shift their focus from quarterly results to stewardship; that the government should move its emphasis from preventing scandals to encouraging long-term investment; and that non-executives should be more focused on supporting managers.

The warning comes as the UK waits to see how the Financial Reporting Council will overhaul the country’s corporate governance code.

The report adds: “The solution to low public trust and productivity is not more rules adding to the caution and compliance burden of boards, but the opposite—encouraging boards to invest in tackling societal problems.”

Laurie Fitzjohn-Sykes, director of research at Tomorrow’s Company, says: “Despite continual reforms and refinements, there is limited evidence that ‘good governance’ is improving outcomes for shareholders and society.”

The report has attracted support from a host of big names in business. Marks & Spencer chairman Robert Swannell says it should prompt boards to “step back and decide what they are there to do and how they add value.”

Tomorrow’s Company says board packs have reached unprecedented sizes—some as large as 250 pages. Mike Wilson, founder of St James’s Place, says: “The length of board packs, board agendas and the background of many NEDs in finance, legal and compliance contribute to NEDs too often seeing their role as ensuring good corporate governance and risk mitigation.”

The report follows Kraft’s recent takeover attempt with Unilever, an event that many commentators view as one company focused on short-term gains, pitted against another company focused on the long term and sustainability.

Unilever’s chief executive Paul Polman abolished quarterly reporting for the company in 2009. In 2014 the requirement to report quarterly was dropped by the regulator, the Financial Conduct Authority, though most companies still produce them.