The Daily Telegraph’s multiple scoop about British MPs expenses claims may not quite have the political explosive power of the Watergate or the Pentagon Papers stories. But it has led to what’s been nicely dubbed a very British revolution, which may or may not end up changing the basic machinery of British political life. That’s not bad as scoops go.

Will Lewis, the Telegraph’s editor must take the lion’s share of the credit. It could have blown up in his face. The risk was apparently judged too big for a couple of other newspapers which turned down the offer of the story of the year. Heather Brooke, an American investigative journalist, gets top prize for getting the story revved up and ready to break by relentless use of the Freedom of Information Act.

But the episode shows the British media as a whole in remarkably robust health and spirits, despite recent laments about threats to the survival of the mainstream media from economic pressures, the spin doctors’ toxic medicines and the loss of public trust.

Consider these pugnacious comments by leading BBC presenters: I can’t see or hear them being uttered by their counterparts in many (any?) other countries as part of a public debate on programmes of a national broadcaster — that is, TV and radio channels paid for by public funds.

Evan Davis to a government minister at ten past eight on the popular BBC Radio 4 Today Programme one morning last week. The minister tried to argue that the present government would be competent to see through an adequate reform of the expenses system for British MPs. Davis: “But you don’t have the moral authority, do you? You’re all responsible for a complete screw-up!”

The language may be unparliamentary, but it’s definitely Anglo-Saxon.

And here’s Gavin Esler, known as a fair but incisive presenter of “Newsnight” on BBC 2 TV. Note that the date was April 14 this year, and the issue was the disclosure — via the political blogger who styles himself Guido Fawkes — of the action of Gordon Brown’s special adviser, Damian McBride, in sending out e-mails slandering opposition politicians in preparation for a concerted online smear campaign based apparently on gossip and inneundo.

A senior government minister, seeking to defend Gordon Brown’s decisive action in sacking Mr McBride at once, argued on live TV that the Prime Minister knew nothing of what his adviser was up to.

Esler: “They say that a fish rots from the head. People sitting at home want to know the truth about a prime minister whom we haven’t had the opportunity to elect, and if it’s true that he has a “dark side” – isn’t he responsible?”

What does the encounter say? And the language used? Everyone can make up their own mind. To me, it is further evidence of a de facto rule, a fact of life about the British — call it a “Britishness test”.

That rule says that, presented with an argument between a TV interviewer and a politician, and provided that the interviewer is demanding more forthright information or an apology while the politician is seeking to evade the issue, the majority of British people will back the journalist. They will say that politicians and public figures must answer the question.

Obvious, you may say. But actually quite rare.

Consider the case of Silvio Berlusconi, the prime minister of Italy, convicted more than once on corruption-related charges in lower courts but each time (so far) able to escape the consequences, thanks to the statute of limitations or changes in the law enacted by a government headed by… Silvio Berlusconi.

Right now Mr Berlusconi faces a challenge from a critical newspaper, La Repubblica, which has started a “ten questions campaign”. The paper has published ten questions directed at the prime minister about his relationship with an 18-year old model on whom he lavished an expensive gift on the occasion of her birthday party. Soon afterwards Mr Belusconi’s wife Veronica demanded a divorce.

The ten questions include this: “Is it true that you promised Noemi you would help her career in show business or in politics?”

Italy’s prime minister, far from submitting to any probing or critical interviews on television, has furiously attacked the newspaper. He has gone a long way towards branding the Italian press as an enemy, just as he had earlier declared “war” on judges, accusing them of a vendetta against him and calling them a “scourge”.

Latest word is that Mr Berlusconi’s soaring popularity with voters has taken a bit of a knock. But on past form he has reason to believe that he can brazen it out, counting on sympathetic coverage on the television channels he owns or controls, as well as the loyalty of the members of parliament whom he leads, to turn the tide of public opinion.

Or take the case of Hungary. Three years ago the then prime minister, Ferenc Gyurcany, was the improbable survivor of a political storm after a recording was leaked of a speech he had made to supporters in which he admitted gross economic mismanagement, saying (according to his own website) “No country in Europe has screwed up as much as we have”, and adding “we lied morning, noon and night”.

How long did it take for that story to come to light so that Hungarian voters could read about it in their newspapers? Five months. The speech was made in May, and its contents were at last revealed in October of 2006.

Or take another extraordinary case from Germany, a country where many journalists have cosy links with senior politicians, and almost all senior figures in the powerful public broadcasting system depend on support from one or other of the main political parties to secure their jobs as editors or reporters. In November 1999 the former Chancellor Helmut Kohl was forced to admit that over a period of several years he had operated a system of secret and unlawful bank accounts for party funding purposes for his favourites within the conservative CDU party. Unproved allegations linked the secret accounts with alleged under-the-counter payments related to large industrial or military contracts.

All those years and none of those well-placed journalists knew enough to blow the whistle? At the very least it was a miserable defeat for the media as a force for disclosing fishy politics. Helmut Kohl was investigated. He refused as a matter of “personal honour” to divulge the number or amounts of cash in the slush fund accounts. The case was soon dropped on the grounds that it would not be in the “public interest” to take it further. Mr Kohl’s reputation was irreparably damaged, but the secrets have stayed with him.

The lesson I take from this catalogue of stonewalls and cover-ups is that disgraceful collusion between journalists and politicians is commonplace.

Exposure of very high level abuses of power through determined media investigation is the exception not the rule. “National security” was cited by the Blair government in the UK when a Serious Fraud Office investigation into alleged bribery in connexion with a huge BAE Systems arms deal with Saudi Arabia was dropped in 2006.

In Britain the political journalists belonging to the exclusive and privileged club of “lobby correspondents” at Westminster has been exposed to sharp criticism and some ridicule for not digging out at least some of the dirt about MPs expenses long ago, despite the great stink the story has created now that it has been exposed.

There are those, too, who think the Telegraph and the rest of the media have got above themselves, that they are behaving like hypocrites, and that the natural order will re-assert itself in time. The order of secrecy about high politics, that is.

Perhaps. But this season of Saturnalia in British public life will never be forgotten. And for now at least elected politicians have learned, in the words of the London Times, to understand that they are meant to be “the servants of the people”, not the other way round.

As was demonstrated by the case of Conservative MP Anthony Steen, who attacked the media after it emerged that he had claimed some £87,000 over a period of years to cover the cost of maintaining his “very, very large house” in Devon, including the cost of inspecting hundreds of trees on his property. “What right does the public have to interfere in my private life? None”, he said in a BBC interview.

The British public seems to have decided, resoundingly, that they do have a right to know about such things when they are being paid for from public money.

Mr Steen has shown, incidentally, that in his case, too, the “Britishness” test works.