It began with what looked like a minor leak, the kind you’d call a plumber for but hope you could contain: reports that Britain’s Home Secretary, Jacqui Smith, had charged two porn films bought by her husband as professional expenses. It has turned out to be a major flood that threatens to bring the roof down on both houses of parliament, exposing the whole rotten edifice of British politics.

For those who’ve been too busy to focus on a scandal in a small client kingdom, here’s the story in a nutshell. A couple of weeks ago the Daily Telegraph, Britain’s conservative broadsheet, began to publish the results of an investigation into expenses claimed by members of parliament. (The investigation may have started as a piece of checkbook journalism: the information was apparently obtained and offered to various papers for £300,000 by a Westminster mole; the others were too stupid, scared or scrupulous to bite.) The Telegraph began by exposing the misdeeds of Labour MPs, but soon turned its attention to the Tories and smaller parties. A collective gasp of outrage rose from the British isles: it seems our representatives have been fiddling the public purse for hundreds of thousands of pounds. While businesses closed and jobs went up in smoke, while pensioners waited months for a few quid to fix the boiler or a draughty door, our taxes were being used to service swimming pools and clean out moats, for fancy furniture and plasma screens and Christmas decorations.

The list of investigated MPs on the Telegraph‘s website reads like a list of status updates from a mad Facebook page: "Margaret Becket made a £600 claim for hanging baskets and pot plants." "James Clappison owns 24 houses but billed more than £100,000, including thousands for gardening and redecoration." "Derek Wyatt billed 75p for Scotch eggs." The big money, of course, is for mortgage payments (some of them fictional) and expenses for second homes. MPs are entitled to money to maintain a home in London as well as in their constituency, but they have to declare one or the other as their primary residence. Many of them turn out to be adept at "flipping"–switching the designation as and when it profits them.

Like cornered beasts the Honourable Members have turned on Michael Martin, the Speaker of the House, a feckless figure who has handled the scandal badly, but not appreciably worse than Prime Minister Gordon Brown. Faced with an unprecedented vote of no confidence (earlier Speakers have been beheaded, but never voted out), Martin is about to resign.

Despite calls for reform of the whole parliamentary system, the country’s loss of confidence in its politicians–and especially in the Labour Party–won’t easily be repaired. The Tories’ pilfering has been at least as bad as Labour’s, but they never claimed to be the party of working people; the Telegraph gave their leader, David Cameron, a three-day start before reporting on his MPs, allowing him to rehearse a suitably smooth and ecclesiastical response. But the real problem for Labour is that the expenses scandal comes after a series of gaffes and blunders by Gordon Brown, including a wildly misjudged vote against allowing the Gurkhas–Nepalese soldiers in the British army–to live here when they retire. And those blunders are as nothing before Labour’s mismanagement of the economy–Brown’s "boom" that turned to bust and billion-pound bank bail-outs–which followed in turn from the Blairites’ severing of the party from its roots. If Britain was in love with Labour back in 1997, it’s now in the divorce court, and it’s not going to change its mind. Like tell-tale credit card bills found in the back of a drawer by a woman who’s been betrayed, the fiddled expenses are only the confirmation of what, in our heart of hearts, we’ve known for a long, long time.