Here is how the "cash for peerages" saga has emerged.
23 OCTOBER, 2007
Assistant Commissioner John Yates, who led the investigation into cash-for-honours allegations, faces a panel of MPs to answer questions on the "lessons learned" from the affair.
9 OCTOBER, 2007
The Crown Prosecution Service says there will be no charges following its cash-for-honours probe involving the Conservative Party.
20 JULY, 2007
The BBC learns that no-one is to face charges in the cash-for-honours inquiry involving the Labour Party.
5 JUNE, 2007
Two of Tony Blair's closest aides are re-bailed by police as part of the cash-for-honours inquiry.
4 JUNE, 2007
Prosecutors confirm that they have asked police for further inquiries into the cash-for-honours allegations.
23 MAY, 2007
Lord Levy says he will step down as Tony Blair's envoy to the Middle East, when the prime minister leaves office on 27 June.
20 APRIL, 2007
The Metropolitan Police hand over their cash-for-honours file to the Crown Prosecution Service. It is 216 pages long and has 6,300 supporting documents. The CPS says it will now review it to see whether any individuals should be charged with any offences.
6 MARCH, 2007
A judge removes an injunction against the BBC. It is then able to report that No 10 aide Ruth Turner had expressed, in document, her concern that Tony Blair's chief fundraiser, Lord Levy, had put to her a version of events which she believed to be untrue. His solicitor issued a statement denying any wrong-doing and saying media reporting of leaks presented a "prejudiced and distorted" view.
3 MARCH, 2007
Attorney General Lord Goldsmith, at the request of the police, obtains an injunction against the BBC to stop it broadcasting an item about the cash-for-honours investigation.
20 FEBRUARY, 2007
Ruth Turner is interviewed by police for about two hours, while answering bail following her arrest in January, on suspicion of perverting the course of justice and of honours allegations.
6 FEBRUARY, 2007
The Crown Prosecution Service says there will be no charges against head teacher Des Smith, who was arrested last year, because of "insufficient evidence".
Downing Street reveals that Prime Minister Tony Blair was questioned by police for a second time on Friday 26 January, shortly before he left for the World Economic Forum in Davos. Mr Blair was interviewed as a witness at the request of the police, and was not arrested.
Labour's chief fundraiser Lord Levy is re-arrested and questioned for several hours on suspicion of conspiracy to pervert the course of justice. He is released on bail and his spokesman says he denies any allegation of wrongdoing.
Downing Street's director of political operations John McTernan was questioned during the previous week for a second time, it emerges. Mr McTernan, seconded to the Scottish Labour Party to run its campaign for May's Holyrood elections, was re-interviewed under caution.
It emerges that Scotland's First Minister Jack McConnell was questioned by police - but not under caution - in December. It is understood Mr McConnell was asked about the peerage nomination of former Lord Advocate Colin Boyd.
Downing Street's director of government relations Ruth Turner is arrested before dawn at her London home. She is questioned over honours allegations and suspicion of perverting the course of justice. She later issues a statement denying any wrongdoing, and Tony Blair gives her his full backing.
14 DECEMBER, 2006
Tony Blair is interviewed by police investigating the cash for honours allegations. His spokesman says he was not interviewed under caution, which means he is being treated as a witness rather than a suspect. It is thought to be the first time a serving prime minister has been questioned by police conducting a criminal investigation.
Scotland Yard's Assistant Commissioner John Yates says police have gained "significant and valuable material" after interviewing 90 people and expect to submit a file to the Crown Prosecution Service in January. The CPS would have to give "careful consideration" to "complex and sensitive legal issues", he adds.
It emerges that all members of the Cabinet at around the time of the 2005 general election, apart from Tony Blair, have received letters from or been contacted in some other way by detectives.
Former Conservative leader Michael Howard says he was interviewed at his home by police investigating the cash-for-honours allegations. He was not under caution and there was no suspicion of him having committed a crime, he adds.
It emerges that police have questioned four Conservative donors, including a businessman whose nomination for a peerage was blocked.
Senior Downing Street adviser Ruth Turner is questioned by police as part of the ongoing probe.
Biotech boss and Labour lender Sir Christopher Evans becomes the third person to be arrested in the "cash-for-peerages" probe.
Prime Minister Tony Blair says nobody in the Labour Party has sold honours in return for financial backing to his knowledge.
It emerges that two ministers, Labour donor Lord Sainsbury and ex-party chairman Ian McCartney, have been questioned by police.
Lord Levy is arrested and bailed by police in connection to the "cash-for- peerages" probe. Lord Levy says he has done nothing wrong and says the arrest powers were used "totally unnecessarily".
The BBC learns that Lord Levy told curry tycoon Sir Gulam Noon he need not disclose his £250,000 loan to Labour on his nomination form for the House of Lords.
Lord Levy, Labour's chief fundraiser, is grilled by a committee of MPs looking at the party funding system.
The Lords' Appointments Committee, which vets nominations for peerages, says it has sometimes been kept in the dark about political loans.
Scotland Yard starts looking at claims that Labour offered the late independent MP, Peter Law, a peerage if he refused to stand at the last election. Labour says the allegation is "categorically untrue".
Police say they are widening their inquiry to cover loans to political parties going back to 2001.
Mr Smith says he will "vigorously" contest all allegations made about him.
Des Smith, a head teacher involved in the government's city academics project, is arrested and bailed by the police investigating the "cash-for-peerages" complaints.
Police say their inquiry is looking at other political parties, not just Labour.
Scotland Yard's Deputy Assistant Commissioner John Yates says his inquiry could be widened into the "arena of corruption" but it is too early to say.
Police ask a committee of MPs to put their inquiry into the "cash for peerages" claims on hold
It emerges that Labour's former general secretary, Matt Carter, wrote to wealthy businessmen telling them their loans would not have to be declared.
Scotland Yard says it is examining complaints that Labour has broken 1925 laws about selling honours.
Labour confirms it was secretly lent £14m ahead of the 2005 election. The party, and the businessmen involved, deny any wrongdoing as loans to political parties made on commercial terms did not have to be disclosed.
Labour's elected treasurer, Jack Dromey, says he did not know wealthy businessmen had lent money to the party and promises to investigate. He says it is wrong for Downing Street to think it can run the Labour Party.
The BBC learns that Mr Patel lent Labour £1.5m.
Chai Patel, head of the priory rehabilitation clinics, protests to the vetting committee for Lords' appointments that his nomination to be a peer has been blocked.
The BBC is told that no-one is to face charges following the 16-month investigation.
Crown Prosecution Service confirms no one will face charges over cash-for-honours allegations.
Assistant commissioner John Yates defends the police's handling of the inquiry.