Paul Vallely: How to change the Bollinger mindset Eat more slowly, a dietician once told me. Greedy people eat too quickly, she said. There is an insatiability about greed - until, that is, you realise you have overeaten. Bankers, it seems, have done the same thing with money. Not all bankers, their defenders say. Just a few. But I am not so sure. The scandal of bankers rigging inter-bank lending interest rates is, apologists for capitalism insist, down to the criminal acts of a few individuals. Yes, it's big and important, because the Libor interest rate they fiddled is used to set the price of $300trn-worth of loans all round the world - on everything from mortgages, credit cards and overdrafts to multimillion-pound business deals. But it's the fault of dishonest individuals, not a structurally flawed system. Let's examine that. Investigators from the Financial Services Authority have the names of hundreds of bankers inside Barclays, and hundreds more in other institutions, involved in at least 257 fiddles. Multiply that by 20 - the number of banks being investigated - and that could well be thousands of names in some of the most prestigious City institutions. "It's hard to believe a policy that seems so systematic wasn't known to people at, or very near the top," Martin Taylor, Barclays former chief executive, has said. The Chancellor, George Osborne, has spoken of "systematic greed." The Labour leader, Ed Miliband, has spoken of "the swaggering culture" in which bankers responded to requests to fix the figures by saying "Done... for you big boy" or "Dude, I owe you big time," with the promise of a bottle of Bollinger. The standard reaction to yet another crisis of confidence in our banking system is to say the rules should be tightened. Libor should no longer be fixed by bankers, but by an independent regulator. Or it should be based on actual inter-bank lending rather than estimates. Or a Leveson-style judicial inquiry should be set up into the warped ethics of British banks. There is a limit to what new rules in an old culture can achieve. Our society is forever creating new regulations, targets, audits and performance indicators to compensate for a growing lack of trust in modern life. The irony is that such measures appear to increase, rather than assuage, our contemporary culture of suspicion. Rules to promote trust, in practice, undermine it because they play down the integrity and good conscience needed to make any system work. If you replace common sense with health-and-safety laws, fair workplace behaviour with employment tribunals, referees' decisions with goal-line technology, and love with prenups, you erode trust rather tha augment it. What we really need is a change in culture. Ironically, Barclays' boss, Bob Diamond, has acknowledged that. "Nothing is more important to me than having a strong culture at Barclays," he said last week, before adding: "I am sorry that some people acted in a manner not consistent with our culture and values." In a lecture last year, he said culture is difficult to define, and even more difficult to mandate, but easy to spot. It is "how people behave when no one is watching." For a bank, that means all employees acting "with trust and integrity" to uphold the fundamental principle that "the interests of customers and clients are at the very heart of every decision we make." The problem for Barclays, and other banks, is they have not one culture but two. The retail side has what high-street banks have always had - a culture of prudence. But the investment side has a culture of risk-taking that has slid into one of greed. The impossibility of these conflicting cultures coexisting in a financial institution became clear in the email exchange between Dude and Big Boy. Dude, at the casino end of the operation, is gambling on the very rate that Big Boy is fixing for us high-street customers. Repeatedly, it is now clear from the FSA investigation, the firewall between the two proved to be champagne-permeable. The Dudes repeatedly persuaded the Big Boys to lie about the rate they were charging, because even a difference of one basis point (a 0.01 percentage) would make literally millions for the bank they both work for. So how do you change the culture of cavalier Big Boy Bollinger arrogance among bankers for whom breaking the rules has become a game rather than an ethical violation? Bob Diamond's suggestion in that lecture was to teach them citizenship. Should we laugh or cry? Or hold those bankers' citizen classes inside our jails? Or send the nation's politicians, lawyers, journalists, advertisers and business leaders along to the classes, too? Perhaps we must be less ambitious and simply acknowledge that the ring-fence which the Vickers commission has proposed between the banking cultures of risk and prudence can never be solid or high enough. What this latest banking scandal suggests is that the two halves of the industry can only survive in completely separate institutions. In that way, the high-risk gambling of investment banking will not be funded by taxpayers who cannot afford to see our retail banking sector collapse.