David Cameron was accused of "threatening recklessly to destroy a generation of work" by a close adviser to Hillary Clinton when he met unionists in January 2010 during the Northern Ireland peace talks.
Mrs Clinton's long-time confidant Sidney Blumenthal emailed the then US secretary of state on January 25th, 2010 to say Mr Cameron, the leader of the British opposition at the time, had intervened at what was a critical stage in the negotiations "in order potentially to gain marginal seats in NI in the case of a hung parliament".
The email is included in about 7,800 pages of emails released by the State Department in response to the controversy over the 2016 Democratic frontrunner's use of a personal email server while acting as secretary of state to President Barack Obama from 2009 to 2013.
In the partially redacted email to Mrs Clinton, Mr Blumenthal includes the copy of an article from the Guardian reporting how then British Prime Minister Gordon Brown was concerned that the Conservatives were endangering the Northern Ireland peace process.
The newspaper reported that Mr Brown was astonished Mr Cameron had convened private talks with senior Democratic Unionist Party and Ulster Unionist Party members at an English country estate.
The meeting led to speculation the Conservatives were attempting to establish a pan-unionist front to limit the success of Sinn Féin and the SDLP in the general election of May 2010.
Jake Sullivan, Mrs Clinton's deputy chief of staff, forwarded Mr Blumenthal's concerned emailed to her, with a note saying: "This is consistent with what Declan and I are hearing," referring to her then economic envoy to Northern Ireland, Declan Kelly.
In another email, on March 6th, 2010, while outlining the latest developments in Northern Ireland, Mr Blumenthal told Mrs Clinton that former US President George W Bush had been asked to call Mr Cameron to tell him that he considered it important for the UUP to stick with the peace talks.
Mr Cameron said he was in favour, Mr Blumenthal reported back to the secretary of state.
Mrs Clinton’s aide later questioned the Tory leader’s talks on an election pact with the UUP and questioned whether he supported the February 2010 power-sharing deal in Northern Ireland.
“It’s unclear what is going on with Cameron. Is he actually pushing for the agreement or not? If he is, does he have any influence? Either Cameron is purposefully not being strong with Empey or he is being spurned, making calls,” wrote Mr Blumenthal.
"If he is not really pressuring Empey, it would be out of a desperate and vain attempt to grab a parliamentary seat in the case of a hung parliament – a seat that is out of his grasp – the Sylvia Hermon seat."
This was a reference to the seat held by the MP for North Down who weeks later resigned from the UUP over its alliance with the Conservatives and was re-elected as an independent in May 2010.
In a later exchange of emails, dated March 6th, 2010, Mrs Clinton pokes fun at then UUP leader Reg Empey over his name.
Mrs Clinton emailed Mr Blumenthal and Mr Sullivan to say Mr Empey had told her the Orange Order didn't vote for a deal on parades as part of a deal to devolve policing powers to Northern Ireland.
When corrected by Mr Blumenthal, who forwarded her an article in The Irish Times showing that the Order was backing the proposals, Mrs Clinton replied: "Empey probably seeing glass 'half empey.'"
Two days later, Mr Blumenthal sent her a newspaper article updating her on the developments in Northern Ireland, writing in the subject line: “Latest news on NI. Empey Dumpty … Sid.”
The State Department has released roughly two thirds of 30,000 of Mrs Clinton’s emails in a move to reassure the American public amid concerns that she was trying to avoid being transparent by using a personal email address for official government business.
