Behind the story: How the expense scandal has rocked Westminster

Were it not for the famous leak of MPs' expenses details to the Daily Telegraph, today's publication of claims on the Internet would have opened a window on the previously secretive world of Westminster allowances.

But after more than a month of daily revelations about MPs' claims for anything from second homes, building work, furniture and gardening to adult films, duck houses and moats, it seems unlikely that much fresh information can remain to shock an appalled electorate.

Information contained on the discs leaked to the Telegraph has rocked the political world to its foundations, costing several prominent MPs their careers and prompting a flight of voters from the main parties to fringe groups in this month's elections.

Today's publication is the result of a legal battle lasting several years against requests under the Freedom of Information Act for details of a handful of MPs' expenses claims.

Despite rulings by the Information Commissioner and the Information Tribunal that the details should be made public, Speaker Michael Martin and the Commons authorities went to the High Court to demand the right to secrecy.

There, three senior judges decided in May 2008 that full disclosure was necessary because of concern over a lack of accountability in the allowances system, particularly the Additional Costs Allowance, which covers the cost to MPs from outside inner London of maintaining a second home while working at Westminster and costs the taxpayer around £90 million a year.

As the case made its way through the courts, details emerged of the so-called "John Lewis list" which set unofficial maximum prices MPs could claim for household items like fridge-freezers, sofas and flat-screen TVs.

Even after the court ruling, MPs fought to hang onto their lucrative second home allowances, voting in July last year to reject reform proposals drawn up by Mr Martin.

The Commons authorities went through the lengthy process of scanning more than one million pieces of documentation onto computer discs, then passing details on to MPs, who were allowed to black out sensitive information like home addresses and bank account numbers.

It was during this process that rumours started circulating that a disc containing completely uncensored details of all 646 MPs' claims had been leaked and was being offered to the press for £300,000.

First victim of the leaks was former Home Secretary Jacqui Smith, who had to defend herself after it was revealed that she listed her family house in Redditch as her second home, while claiming her main residence was a room in her sister's London house.

Ms Smith was embarrassed again when it emerged she had claimed £10 for adult films watched by her husband.

But it was not until the Telegraph obtained a copy of the leaked material that the full scale of abuse and rule-twisting at Westminster became clear.

The flood of revelations, starting on May 8, has forced dozens of MPs from all the main parties to defend themselves against claims that they exploited an over-generous and lightly-monitored system to rake in thousands of pounds of taxpayers' money.

Perhaps the most surprising revelation - and one which might not have been uncovered if the public had seen only the censored details expected to be released today - was the extent to which MPs "flipped" their second homes to maximise claims.

Flipping allowed members to change the designation of the second home on which they could claim allowances, so as to be able to furnish, renovate and decorate two or more properties at taxpayers' expense.

In some cases, it even appeared the practice was used to avoid the capital gains tax payable on the sale of a second home.

Amid a tide of public anger, an independent shake-up of the allowances system by the Committee on Standards in Public Life was brought forward, and is now expected to report by October this year.

Prime Minister Gordon Brown offered a public apology on behalf of all MPs.

Meanwhile, the John Lewis list was dumped and the Commons agreed to restrict the items that could be claimed for under the second homes allowance.

And both Labour and the Conservatives set up their own panels to judge MPs found to have made particularly questionable claims.

Already, five Labour MPs have been told they cannot run for the party in the upcoming election and a number of Tories have agreed not to stand again. One Labour MP, Ian Gibson, has quit the Commons, forcing a by-election in his Norwich North constituency.

A series of ministers have quit the Government - often citing other reasons than the expenses scandal - culmininating last night with Kitty Ussher's departure from the Treasury after being accused of dodging capital gains tax.

But perhaps the biggest scalp of all was that of the man who led the fight to stop the light being allowed in on the expenses system in the first place, Commons Speaker Michael Martin, who yesterday took his place in the famous green chair for the last time and will resign his post on Sunday.