Here are key quotes from Conservative party leader Iain Duncan Smith after learning he faces a Commons investigation by Parliamentary commissioner Sir Philip Mawer into the running of his office.
BBC political editor Andrew Marr asked Mr Duncan Smith if it was a blow to him that an inquiry had been launched:
"Not at all. Actually, I'm very pleased that he has now said that he is going after all the evidence, because I have had to put up with weeks and weeks of drips and leaks from anonymous sources...
"These are really just cowards lurking in the shadows and what I say is I have presented everything to him openly and honestly and I asked for this inquiry...
"I believe I will be exonerated at the end of it."
Mr Duncan Smith was asked about alleged evidence from his private secretary Christine Watson, that she was "working solely" as his diary secretary during the period of this controversy.
"What she was pointing out was the need for change in that office because things were not working and that is exactly the reason why my wife Betsy was working with me at that time.
"We had to set up an office from scratch and what we were trying to do was combine the roles of the constituency office and the leader's office...
"My wife was working for me... She was coordinating, acting as a progress chaser with all the various aspects - my private secretary, my diary secretary - making sure things ... were not falling through the cracks."
Referring to the "anonymous sources" involved in this episode:
"These cowards have gone after my wife as a way of getting to me and I think it is intolerable...
"I love my wife dearly and she has supported me over 10 years in my office. She knows everything about what I used to do and she was part of that transition. Absolutely critical.
"I have explained that to Sir Philip and I think anybody who wants to come after me, come after me, but you don't go after my wife who is decent."
Asked how he felt about people in his own party coming after him:
"These anonymous sources, at the end of the day, are cowards hiding in the shadows who are simply using the possibility of television and media to place difficulties in my way.
"I say to them and anybody else, I'm an honest and straightforward man and the wife that I love has worked with me for 10 years.
"If people don't like what I do politically, fine, but what you don't do is try and hurt those who I love and who are nearest and dearest to me.
"I have nothing to hide from this."