Gordon Brown's proposal to scrap MPs' second home allowances was inadvertently revealed ahead of schedule in another Downing Street photographic give-away today.
The Communities Secretary Hazel Blears was clutching a copy of the proposals as she left Cabinet this morning. Photographs clearly show the plans to replace the perk with a daily attendance allowance.
The slip came less than a fortnight after Bob Quick was forced to resign as Assistant Commissioner of the Metropolitan Police when he accidentally revealed operational details of an anti-terror raid by displaying a secret memo as he arrived to brief Mr Brown at Number 10.
Ms Blears apologised to Mr Brown for her own blunder and was said by aides to be feeling "sheepish" about the incident. A spokesman for her department stressedthe papers were not restricted and were related to an imminent announcement.
By the time her error became known, the proposals on MPs' expenses had been unveiled by Mr Brown on the Downing Street website and by Commons Leader Harriet Harman in a statement to the House.
The controversial second home allowance for MPs could be axed in days after the Prime Minister demanded an urgent Commons vote on reforms.
In an attempt to calm a growing storm over taxpayer-funded Westminster perks, Mr Brown pre-empted a summit with other party leaders and an independent inquiry by calling for a vote as early as next week.
Mr Brown set out his proposals to make the system "simpler and less generous" in a video posted on the Number 10 website shortly before they were formally published for MPs by Commons leader Harriet Harman.
He said it was vital to take immediate action to restore confidence that MPs were there to "serve the public and not there to serve themselves" and warned MPs they needed to show "humility".
Under his proposals, the second homes allowance would be replaced by an independently-set flat rate daily allowance based on attendance.
Ministers who live in grace and favour homes and MPs living "within travelling distance" of Westminster would be banned from claiming it, though there will still be an allowance for London MPs.
Receipts would be required for every item claimed by MPs, however small, under the terms of the interim reforms - which could be in place by 1 July.
Video: Gordon Brown outlines his expenses proposals
There would also be "greater transparency" of earnings from MPs' second jobs, said Mr Brown - who today wrote to Tory leader David Cameron and Liberal Democrat leader Nick Clegg offering to meet to discuss the proposals in the next week.
Under the proposals, all staff appointed by MPs would become direct employees of the House of Commons which would set their employment terms and pay.
This measure is designed to address concerns over the employment of MPs' relatives.
An independent inquiry into MPs' pay and perks by the Committee on Standards in Public Life has already been brought forward to report by the end of this year.
But the Prime Minister, under pressure to act after Cabinet colleagues including Home Secretary Jacqui Smith were drawn into the controversy, said even faster action was needed.
Mr Brown said: "The issue of expenses is casting a cloud over the whole of Parliament. So Members of Parliament need to have the humility to recognise that the country has lost confidence in the current system," he said.
"To restore our faith in Parliament and the good that it can do on the public's behalf, we must commit to tightening up the system of allowances urgently."
The chairman of the Committee on Standards in Public Life, Sir Christopher Kelly, warned that the issue of MPs' allowances cannot be resolved by a "quick fix".
Sir Christopher confirmed that his committee's comprehensive review of the expenses system - due to be launched on Thursday and to report towards the end of this year - will go ahead as planned.
He said: "It is no surprise to me that the political parties want to deal with this themselves.
"The headlines continue and the prospect of publishing receipts in July makes this a very damaging issue for them.
"I have warned on numerous occasions that this is not something that can be solved by a quick fix.
"The fundamental review we are carrying out is still needed and will still go ahead.
"This issue needs to be dealt with properly so that the public can have confidence in the integrity and probity of the system.
"I will be publishing our 'issues and questions' paper on Thursday and will hear evidence from all interested parties and the public."
TaxPayers' Alliance chief executive Matthew Elliott said: "It's good to see that the Prime Minister has finally woken up to the public's anger over MPs' expenses.
"Far too many MPs have been ruining public confidence in Parliament by using allowances to feather their own nests, and we need concrete steps to prevent this abuse in future.
"A daily attendance allowance can work, but it must be tightly policed so that we avoid the kind of abuse seen in Brussels.
"It has taken a long time for the Government to take action, but at last taxpayers' concerns are being taken seriously."
Mr Brown's spokesman denied that the Prime Minister's initiative had pre-empted Sir Christopher's inquiry.
"Of course it is right that there needs to be a proper, long-term, sustainable solution that needs to have the trust of the public and that is why it is right that Christopher Kelly has been asked to look at that," said the spokesman.
"What we are setting out today are interim proposals to take effect in the interim period before Kelly reports."
Any changes to the expenses system are ultimately a matter for the House of Commons collectively and not the Government, said Mr Brown's spokesman.
But he said it was right that the Government set out its preferred options as a basis for debate, both between the party leaders and on the floor of the Commons.
The proposals were unanimously agreed by Cabinet this morning and ministers and other MPs on the Government payroll will be expected to support them in the Commons, though it is understood that Labour backbenchers will be granted a free vote.
MPs may not know the value of the proposed daily attendance allowance by the time of the Commons vote.
Under the proposals, MPs would continue to appoint their own staff and would be allowed to give jobs to family members, but they would be directly employed by the House of Commons authorities, which would be responsible for employment terms, contracts and payment of salaries.
The spokesman said: "It is the view of the Prime Minister and the Cabinet that it is important to act now in order to deal with this issue, while of course respecting and waiting for the comprehensive analysis form Sir Christopher Kelly when that comes later.
"These proposals are designed to be fair, reasonable and straightforward. They respect the fact that the overwhelming majority of MPs do a good job and that being an MP and representing constituencies - particularly those outside London - does impose additional costs."
Mr Brown wants the issue to be resolved "in as consensual a way as possible" and hopes to meet the leaders of the main opposition parties within the next week, said the spokesman.
The Prime Minister said the changes would save the taxpayer money but suggested that the rules, not MPs themselves, were to blame.
"Every MP I know wants to live by the rules but for too long some of these rules have been insufficiently clear and we need to make the rules clear and we also need to save money," he said in the broadcast, which is to be posted on the YouTube website.
"So I am announcing today urgent proposals to make our system of MPs' allowances and expenses simpler and less generous."
He said the Committee would recommend "permanent changes".
"But I believe we have to act urgently with interim proposals... and I want a vote to take place to overhaul the current system as early as next week."
Later he appeared to confirm that a vote was expected within 10 days.
"We will ask the House of Commons to approve them next week," he said.
On second jobs, he said "every payment should be declared with a full description of who is paid and what it is for and who paid it.
"There should also be a full declaration of the hours worked for the payment received."
Mr Brown said the "vast majority" of MPs did an excellent job.
"They are in public service not for what they can get but for what they can give," he said in the video.
Mr Brown said he hoped to reach consensus with other party leaders, who have already published reform plans and called for a meeting this week ahead of a Commons vote.
He is also meeting Sir Christopher today to discuss the interim proposals.
"With these changes, I hope the work of MPs can become recognised again for what it should be: a service to the public," the PM concluded.
Liberal Democrat leader Nick Clegg warned against bringing a Brussels-style daily allowance system - widely seen as open to abuse by MEPs - to the Commons.
Mr Clegg told BBC News: "I don't think bringing the Brussels gravy train to Westminster is the way to solve the lamentable system of MPs expenses.
"The great danger is this: you are giving MPs a cheque simply for turning up for work and the MPs don't have to prove that they need that money or what they are going to spend it on."
But he said all party leaders were united "in a desire to fix" the current system.
No 10 said later that Mr Brown had now met the chairman of the Committee on Standards in Public Life.
A Downing Street spokesman said: "The Prime Minister met Sir Christopher Kelly, chair of the Committee on Standards in Public Life, earlier today.
"The Prime Minister asked him to continue his work on MPs' allowances and said that he had great confidence in his review."