Even after PPI, forex and the financial crisis, many of the directors who presided over scandal remain in public life.

There was a time when bank bosses took at face value Ogden Nash’s satirical poem Bankers Are Just Like Anybody Else, Except Richer. Not any more. These days most bank executives realise they are different in that their actions can blow up the global economy, bring nations to their knees and impoverish millions.

City watchdogs say they also grasp that global banking can be economic nitroglycerine and are getting to grips with the complexity and myriad international connections that make it so hard to track and render safe.

Yet while bankers have sometimes apologised (no tears, though) and regulators have drawn up new rules almost every month to prevent wrongdoing, there is every reason to remain wary.

Last week all eyes turned to the banks caught rigging the foreign exchange markets. Dollars, euros, sterling, it didn’t matter – traders knew they could fix the price, make a bundle and have a laugh while they were at it.

Incredibly, the antics at Royal Bank of Scotland and HSBC went on beneath the noses of executives under strict orders to look out for such behaviour. Regulators, supposedly chastened by criticism of their negligence during the financial crash, contrived not to go looking for traders’ messages congratulating each other on their brazen rule-breaking.

George Osborne has stepped into the fray, demanding examples be made of the perpetrators. To make good his challenge, the chancellor promised the Serious Fraud Office all the funds it needed to pursue prosecutions.

It is gratifying that a senior minister wants wrongdoing in the City to be taken seriously. Osborne has toughened the regulatory regime and in some respects gone further than his counterparts in other countries.

However, Osborne is not a bystander. The Treasury, alongside Vince Cable’s business department, could have punished many of the worst offenders in the banking crash and every subsequent scandal were it not for their seeming air of reluctance.

Payment protection insurance is the costliest of all the scandals. It beats the £11bn over mis-selling of endowment mortgages of the late 1990s and £12bn for personal pensions. PPI has so far cost the banks 15bn in compensation and almost another £3bn in administrative costs.

But more than a decade ago, the Guardian unearthed the possibility that PPI sales were a scam. It pressed the regulator for an investigation into claims that banks – some of which were making 10% of their global profits from this one product – were involved in a racket. Even now those allegations lie dormant.

Why are Lloyds bosses, who have set aside more than £10bn to cover the bank’s mis-selling bill, not facing bans as directors? Should Marcus Agius, the former chairman of Barclays, sit as non-executive chairman of the consultancy PA and chairman of the trustees of the Royal Botanic Gardens at Kew, after presiding over the Libor scandal? Should he not be serving some sort of penance and be banned as a director? Likewise all the other board members of the banks?

If there is money to pursue traders for rigging foreign exchange trading, there should be funds to prosecute them all. The public deserves it, even now. Many of the people who brought their banks, and nations, to the edge of collapse are still in public life.

Cable has the report on the collapse of the Halifax on his desk. Next to it are proposals to ban its executive board members as company directors. Neither has seen the light of day and there is no indication from his department when that might happen.

It seems that politicians and regulators have succumbed to the argument that the finance industry has suffered enough. The industry still exports many of its services, and in doing so supports the nation’s balance of payments. The professional-services firms that hang on its coat-tails are likewise good for the economy.

There may be some truth in this, but without tougher measures now – especially banning bosses found wanting from taking company directorships or taking away bank and individual licences to trade – the industry will remain complacent and greed will still have its rewards.