The expenses scandal is the biggest shock to the political system since I began pounding the Westminster beat 25 years ago. To borrow the language beloved by campaign strategists, it has "cut through" to the public in a way that very few political events do.
The headlines about taxpayer-funded moats, duck islands, adult movies, bath plugs and £400-a-month food bills will do lasting damage not just to the careers of many MPs but to the system as a whole. It is hard to imagine anything having such a corrosive effect.
Probably it has gone too far now. The image it paints of all politicians with their snouts in the trough is unfair on the many who came into public service to give not take. But there is no turning the clock back.
The expenses affair has been mishandled from start to finish. Politicians in all parties were slow to realise the threat from the Freedom of Information Act. Labour's record on allowances makes it a bit rich for the party to claim credit now for passing the Act.
In March last year, the "Commons authorities" decided to try to put off the evil day by appealing against a FoI tribunal ruling that the second home allowances paid to 14 prominent politicians should be disclosed. I understand that only two members of the House of Commons Commission were present: the Speaker Michael Martin and the Commons Leader Harriet Harman. She has radical reforming instincts but presumably on this occasion was doing what Gordon Brown wanted: to kick the expenses affair into the long grass. The test case was lost, paving the way for yesterday's publication of the payments made to all 646 MPs.
The outgoing Speaker was part of the problem but he was right in his farewell blast on Wednesday to point a finger of blame at Mr Brown. Allies admit the Prime Minister was slower to "get" the expenses issue than David Cameron or Nick Clegg. Perhaps he hoped it would go away, at least until after the general election. Perhaps it seemed trivial compared to trying to save the world.
Some 33 of Mr Brown's ministers voted against a proposal to abolish the "John Lewis list" of allowable claims for second homes in July last year. Knowing the vote would be lost, the Prime Minister didn't turn up.
True, Mr Brown called this year for the inquiry by Sir Christopher Kelly's Committee on Standards in Public Life. But then he was panicked into pre-empting its findings by rushing out his own proposals in that infamous YouTube video.
Things got messier. His "clocking on" proposal was quickly killed off by a revolt by MPs. Several other reforms have been rushed through, such as a ban on using the second homes allowance for furniture and fittings and for all claims to require receipts. This leaves Sir Christopher cast in the role of forensic expert called in to examine the body politic when the post mortem examination has been held and the inquest has already reached a verdict.
The reaction of the Commons authorities when The Daily Telegraph obtained the uncensored version of the expense claims in May was typically flat-footed. Even in a crisis, the Westminster machine turns slowly. Surely they could have been published before yesterday? Surely, as Mr Brown acknowledged at a press conference in Brussels, so much information did not need to be blacked out, symbolising the grudging acceptance of the FoI ruling instead of making a virtue out of a belated openness?
Yesterday was not the end of the affair. The receipts that are now visible will find their way into campaign literature across the land at the general election. It is a good time to be a challenger, not a sitting MP.
Voters will have long memories. It will surely take more than one election to clean up the system in the eyes of the voters. Even a change of government would not guarantee it.
Trust is easily lost and hard won. It is even harder to win back when lost in such a spectacular fashion.
Who's to blame?
1. Gordon Brown, Prime Minister
Slow to realise potential damage from the expenses affair. His plan to replace second homes allowance blocked by MPs' revolt.
2. Harriet Harman, Leader of the Commons
Backed appeal against Freedom of Information tribunal ruling that MPs' expenses should be revealed.
3. Michael Martin, outgoing Commons Speaker
Backed moves to keep expenses claims secret. Failed to secure Commons backing for reform.