-- Paul Taylor is a Reuters columnist. The opinions expressed are his own --

PARIS (Reuters) - They’re at it again.

No sooner has the financial system begun to stabilize than Big Finance is reverting to its old ways -- aggressive hiring, remuneration on steroids, wriggling out of regulation or threatening to decamp to evade tougher supervision.

These are is not the rantings of some crypto-Marxist City-basher, but the considered view of one of Europe’s most thoughtful financial regulators.

In testimony to the House of Commons on Tuesday, FSA chief Lord Adair Turner voiced concern that the industry was failing to learn the lessons from the “biggest financial crisis in the history of market capitalism.” Regulatory exhaustion and the first green shoots of recovery could prompt “some drawing back from the degree of radicalism that we require,” he said, raising the prospect of another such crisis in 10 or 15 years’ time.

Turner cited investment banks’ aggressive hiring of traders among his concerns. Others would add the return of bumper bonuses, the casting off of restraints on top executives’ pay, and threats by banks and hedge funds to desert the City if the EU or the UK enact onerous new rules.

There are plenty of examples. Last week, 10 of the biggest U.S. banks repaid $68 billion in U.S. taxpayers’ bailout funds in a race to extract themselves from government restrictions on pay for senior executives.

Citi C.N, prevented from repaying its $25 billion in TARP funds, is reported to be planning to raise employees' base salaries by as much as 50 percent this year to offset smaller bonuses.

In Brussels, there is talk that Internal Market Commissioner Charlie McCreevy, the pope of “light touch regulation,” is busy watering down his officials’ proposals to regulate the vast and opaque trade in over-the-counter derivatives.

Where banks and financial market players feel they are not getting their way, some are threatening to vote with their feet.

Hedge fund managers warned the UK Treasury at a recent meeting that some funds could desert London for Switzerland to avoid EU regulation. And even the big banks are dropping veiled hints that they could move elsewhere.

A senior continental European regulator says he sees growing signs that the financial services industry is playing for time in the belief that it will be back to “business as usual” soon provided it can see off the drive for rapid and sweeping regulation.

Regulators are not necessarily helping themselves. Debates over the degree of future intervention, and turf battles between different regulatory bodies, are sapping momentum in the United States, Britain and the EU.

There is legitimate concern that hasty, ill-drafted reforms will merely create a new set of problems in the future. But regulators have a limited opportunity to impose meaningful changes. They must not allow themselves to be blown off course.