By Nick Assinder
Political correspondent, BBC News website
John Yates, the senior police officer who probed the cash for honours affair, said it all within about 15 minutes of starting his evidence to the Commons public administration committee.
He said there had been those who failed to co-operate fully with his inquiry and that: "We were treated as a political problem rather than a criminal problem."
Mr Yates said he did not receive full cooperation
Pressed to name names, he refused, saying: "I think it would be quite obvious to everybody who that was."
For those in the room who were not sure what he meant, the MPs suggested: "Downing Street?"
Yates of the Yard would not be drawn on that, declaring with a wry smile that during his lengthy investigation he had learnt that "Downing Street" meant many different things.
Neither would he confirm, then, that he meant the prime minister's office.
There then followed a lengthy, mostly even tempered exchange which sought to get to the heart of the crisis which rocked the government and saw the unprecedented sight of the then prime minister, Tony Blair, twice interviewed by police and close aides arrested and questioned.
Many of the questions fired at Mr Yates, CPS head Carmen Dowd and QC David Perry, could not be answered because of the failure to bring charges in the affair.
Mr Blair was twice questioned in the affair
All had agreed the MPs questioning should not become a "police investigation by other means".
None the less, Mr Yates and the other witnesses did throw some light onto the affair.
They confirmed they had known from the start it would be difficult to prove a link between offers of peerages and cash donations - over and above what they had been told had always gone on.
But, as Mr Yates declared, they did their job. "What we had was there were inferences, there were indications that evidence may be available."
Later in his inquiry there was evidence that gave him "increased confidence that there was something there".
However, there then came the problem of the alleged conspiracy to pervert the course of justice which sent the inquiry in a different direction.
And Mr Yates made it clear it was that which had meant the inquiry had dragged on but no details were given or comments made on the specific circumstances.
Throughout the police investigation, all involved denied any wrongdoing.
This two-hour session, if Tony Blair was still in No 10, would no doubt land him with a fresh political headache.
But the fact he and those at the centre of this row have moved on will take the heat out of this MPs' inquiry - whatever conclusion they come to when they draw up their final report.