Sir John Sawers, Britain's current ambassador to the United Nations, told the BBC that Iranian officials had privately admitted their role in supporting insurgents' roadside bomb attacks on British and US troops.
"The Iranians wanted to be able to strike a deal whereby they stopped killing our forces in Iraq in return for them being allowed to carry on with their nuclear program," Sawers told the BBC.
He paraphrased the terms of the proposed deal as: "'We stop killing you in Iraq, stop undermining the political process there, you allow us to carry on with our nuclear program without let or hindrance'."
Apparently, the mullahs' official had proposed the deal in a series of they had with their counterparts in European capitals.
"There were various Iranians who would come to London and suggest we have tea in some hotel or other," Sawers told the BBC.
"They'd do the same in Paris, they'd do the same in Berlin, and then we'd compare notes among the three of us."