To tax experts, last night’s gory Panorama exposé came as little surprise.

The dossier at its heart relates to more than 130,000 suspected tax-dodgers who ferreted billions away at HSBC Private Bank Suisse SA.

Banking in Switzerland is not illegal, but failing to tell your country of residence about it is.

The sensational documents were compiled by whistleblowing IT worker Herve Falciani over two years to 2007.

He copied rafts of evidence incriminating his bosses, whose scams included redefining individuals as corporations to duck new EU transparency laws.

But when Falciani raised the alarm he found himself targeted by the police, accused of industrial espionage.

After being arrested and questioned in 2009 he fled to France, where he lives to this day despite a warrant issued by Switzerland.

His dossier was seized by the French authorities, who subsequently passed details abroad.

In Britain HM Revenue and Customs was told of 6,000 suspects. But after that was whittled down to 3,600, only 1,000 have been fully probed, netting just £135 million despite years of evasion.

And only one individual — multimillionaire property tycoon Michael Shanly — has ever faced prosecution.

HMRC has applied only gentle pressure on the rich and powerful individuals at the scandal’s heart.

All these facts are already known, but the dossier shows how far bankers went to encourage tax-dodging.

It also lifts the veil of secrecy on the wealthy account-holders.

British authorities have sat on this information for years — even as HSBC’s then-chair Stephen Green was welcomed into the bosom of PM David Cameron’s government.

Now pressure is mounting on the banks, the Tories and Lord Green himself.