During a briefing at the London School of Economics in November 2008 on the global market turmoil, the Queen famously asked the question on many minds: given that the financial crisis was so big, why did nobody notice it coming? Her host, Professor Luis Garicano, suggested: “At every stage, someone was relying on somebody else and everyone thought they were doing the right thing.”

A lack of accountability was clearly the flawed reality that proved so dangerous – and, to put it mildly, so disappointing, after 15 years of effort in the UK to develop an oversight framework for companies, including banks.

In addition to external regulation and auditing, corporate governance is the system by which companies are directed and controlled while balancing the interests of different stakeholders – shareholders, customers, management, employees and the community.

The first version of the UK’s Corporate Governance Code was published in 1992 by the Cadbury committee, which was set up after the collapse of Polly Peck, whose audited accounts turned out to bear little resemblance to the company’s actual financial position.

Sir Adrian Cadbury saw the problems as “loose accounting standards, uncertainty over the control responsibilities of directors and competitive pressures on companies and on auditors”. Many boards “had too much of the flavour of a club, with collegiality taking precedence over constructive questioning”.

So a code was developed, to clarify the duties of the board. Companies are now expected to follow the guidance on effective board practices. If they don’t, they need to explain why – and to convince shareholders.

The code is not static. There have been several iterations, most notably after the 2003 Higgs review, which focused on the important role of independent, non-executive directors (NEDs) after the Enron scandal in the US, where the NEDs appeared “asleep at the wheel”.

So there was considerable effort to develop a strong oversight regime before the financial crisis. However, the collapse of several banks six years ago was indisputably – though not solely – a corporate governance failure, revealing fatal weaknesses in board oversight. Investors, too, were found lacking; one of our responsibilities is to ensure that companies we invest in are well governed.

The regulator’s report into Royal Bank of Scotland’s failure criticised the board in a number of respects: it was too big – with 17 members; there was “little significant disagreement”, with “group think” reflecting the board’s homogeneity; and there was insufficient challenge of the CEO. The composition of the board was an underlying factor, with Lord Myners suggesting in April 2008 that “the typical bank board resembles a retirement home for the great and the good”.

Much thought has since been given to how to make boards more effective. They are now smaller, with a FTSE 100 average of 11 members, and they are constructed as teams rather than as a collection of distinguished CVs. Diversity of thought, personality and background among directors, as well as their technical skills and experience, are now key.

But have the changes been radical enough? The 30% Club and the Davies Committee, both primarily focused on better gender balance, recently co-hosted a seminar to consider more generally how far boards have evolved.

There’s certainly been tremendous progress towards more female directors; now nearly 23pc of the FTSE 100 total (up from 12.5pc at the 30% Club’s launch in 2010), with no all-male FTSE 100 boards and “just” 28 all-male FTSE 250 boards, down from 131 (yes, over half).

Gender diversity is an important contributor to diversity of perspective: men and women are different and we work more effectively together. But encouraging more women on boards has been a useful place to start rather than finish the needed shake-up.

The seminar brought together chairmen, NEDs, executive search professionals, board effectiveness reviewers, the Financial Reporting Council (responsible for the code) and investors.

The report card was encouraging about both speed of travel and degree of effort. Chairmen outlined thoughtful processes around new board appointments, starting with identifying gaps in existing directors’ skill sets.

Dr Tracy Long, who founded Boardroom Review over a decade ago, corroborated that much has changed, based on her experience conducting 130 board reviews. Investors, too, now engage regularly with companies on board composition and succession planning – and are willing to vote against those not doing enough to improve diversity.

However, the discussion highlighted that these efforts are not yet all joined up. Investors pointed out that board effectiveness reviews are not typically shared with them. Would the reviews of Tesco’s board have provided useful clues about its oversight, before the recent problems?

In the absence of companies volunteering their reviews, we can create a feedback loop from investors. The Investment Management Association is exploring a UK Board Confidence Index, already used by investors in Australia to rank corporate boards and chairmen against various criteria. It has spurred companies into action.

There are other areas where a more revolutionary approach is needed. The average age of non-exec FTSE 100 directors is still over 60, suggesting Lord Myners’ jibe still applies: few young people would consider or be considered for directorships. There is almost no diversity among chairmen (just two females in the FTSE 100, for example) suggesting a “club” still prevails. There are relatively few executives serving as non-execs on other companies – useful for ensuring that board thinking is current.

Most importantly, there is little evidence of radical or disruptive ideas being welcomed. Bank boards were too comfortable in the run-up to the crisis: the lesson is there needs to be a degree of discomfort. Big boards and layers of committees are not designed to create the out-of-left-field thinking that might anticipate the next disaster.

The painful truth is that financial institutions are probably still too big and complex to be truly governable. So while boards are now more carefully composed and more accountable, let’s not kid ourselves that they offer an insurance policy. With storm clouds gathering over the European economy, jittery markets and widespread uncertainty over the long-term implications of quantitative easing, the onus must be on all of us – especially shareholders – to keep on questioning and to flag problems that will inevitably arise.

This article was written by Helena Morrissey, founder of the 30% Club, and originally appeared in the Sunday Telegraph