Iain Duncan Smith has been cleared by Parliament's watchdog over claims about his private office. BBC News Online explains the controversy:
What was the complaint against Mr Duncan Smith?
Mr Duncan Smith continued to employ his wife Betsy as his diary secretary, working from home, for some time after becoming Tory leader. She was paid out of the Commons allowance that all MPs receive to run their offices.
Investigative journalist Michael Crick claimed he had evidence that she was not doing enough to justify her salary.
So what did the Tory leader have to say about the claims?
He bullishly insisted he was innocent of all charges, insisting his wife worked for him legitimately over 10 years and produced a 40-page dossier to prove it. He said people "hiding in the shadows" were just trying to get at him through his wife.
Is it unusual for MPs to employ their wives as secretaries or assistants?
Not at all. At least 40 MPs have family members working for them in some way or another - and they say it can help ease the strains put on their relationship by life at Westminster.
MPs can claim up to £74,985 from House of Commons funds to staff their offices both inside Parliament and back at their constituencies.
Mr Duncan Smith said his wife was contracted from 1997 to work 25 hours a week and received no more than £15,000 every year while working for him - and a total of £11,000 in the last year.
What has happened now?
Parliament's sleaze buster, standards commissioner Sir Philip Mawer has spent months investigating the inner workings of Mr Duncan Smith's private office.
And what's the result?
Sir Philip dismissed the main claim that Mrs Duncan Smith had not done enough work and said he had seen nothing to cast doubt on the honesty of her and her husband.
But he did say two other officials - and in some case - Mrs Duncan Smith should have been paid out of the money given to opposition parties, not out of an MP's parliamentary staffing funds.
The problem was that they were doing party political, rather than parliamentary, work, he says, and there was a misunderstanding.
MPs on the Commons standards committee said it did not accept Mr Duncan Smith had broken Parliament's code of conduct, not least because the guidelines over paying staff were ambiguous.
What now for Mr Duncan Smith?
Sir Philip says former senior Tory officials Vanessa Gearson, Jenny Ungless and Mark MacGregor told him they had seen no evidence of Mrs Duncan Smith doing work for her husband which would have justified her being paid out of his parliamentary allowances.
But other staff from Mr Duncan Smith's office were able to detail the kind of work she did.
The watchdog says it is odd senior Tory officials did not know what she did.
But that can be explained by the fact she was a "back room character" who was not working at Westminster and who only directly contacted a few other staff.
There was also confusion over when Mr Duncan Smith first set up his office on becoming leader.
And what does Mr Crick make of the report?
He says he accepts the findings, but says any decent journalist given the evidence he received would have been negligent if he had not pursued it.
The MPs said they had "grave doubts" about Mr Crick's own investigative techniques, but he insists everything was perfectly proper.
What now for Mr Duncan Smith?
The ex-Tory leader says he is "over the moon" he has been exonerated and now wants to move on.
He says the allegations may well have played a part in him losing his job at the Tory helm last year but argues he is not interested in fighting old battles.