LORD MANDELSON, the business secretary, penned a devastating critique of Gordon Brown’s character, labelling him “insecure”, “self-conscious” and “angry”, according to leaked e-mails.

The memos are understood to state that Mandelson thought Brown was too preoccupied with celebrity gimmicks and should concentrate on “strategic policy formulation” rather than “telling people that you watch The X-Factor”. Only last week the prime minister telephoned to inquire about the health of Susan Boyle, the Britain’s Got Talent runner-up who had been admitted to the Priory suffering from exhaustion.

Mandelson also suggested that Brown could not win the next general election unless he brought back more heavy hitters into the cabinet.

The disclosure of the e-mails, which claimed that the prime minister tried too hard to be a “normal” person, comes just two days after Mandelson was promoted in the cabinet reshuffle to become first secretary of state – deputy prime minister in all but name.

While publicly, Mandelson has been helping to save Brown’s stricken leadership, the e-mails reveal his private concern about the prime minister’s suitability for high office.

His remarks have echoes of the devastating accusation that Brown suffered from “psychological flaws”, a remark attributed to Alastair Campbell, Tony Blair’s former director of communications.

It also follows disclosures in The Sunday Times that Mandelson “dripped pure poison” about Brown into the ear of a senior Conservative just weeks before he was recalled to the cabinet last October.

The Mandelson memos are understood to have been written in January 2008, nine months before Brown offered him a peerage and a place in the government.

The comments about Brown were made in an e-mail exchange with Derek Draper, the shamed former blogger, who had previously been an aide to Mandelson.

Draper was also involved in the Damian McBride smear e-mails scandal, when Brown’s spin doctor was caught plotting to spread false allegations about the private lives of prominent Conservatives.

The McBride e-mails had been sent to Draper’s private account and were then leaked to Paul Staines, the political blogger known as Guido Fawkes. When the smear memos were published two months ago Draper was forced to quit as editor of LabourList, a party website.

It is understood that the communications between Mandelson and Draper come from a cache of documents acquired by Staines that included the McBride memos. The blogger yesterday sold the Mandelson e-mails to a tabloid newspaper for a five-figure sum.

The discussion of Brown’s character flaws emerged in part of a wider e-mail discussion between Mandelson and Draper, on the subject of a book, The Political Brain: The Role of Emotion in Deciding the Fate of the Nation, by the American psychology professor Drew Westen.

Westen argues that the most successful politicians are ones who appeal to voters on an instinctive emotional level. Political leaders – such as Brown – whose style revolves around the use of rational arguments tend to be less successful.

As a trained psychotherapist, Draper was interested in Mandelson’s view on the book’s thesis and how it related to the prime minister.

It is understood that Mandelson, who was then working in Brussels as the European Union’s trade commissioner, referred to Brown as “complex”, “insecure”, “self-conscious” and “angry”.

He also discussed Brown’s interest in populist politics.

This is a criticism that is regularly levelled against Brown, including last week when he made entrepreneur Sir Alan Sugar, the Apprentice star, a peer and gave him a government job.

It is understood that Mandelson said that Brown’s premiership had not recovered from its early days in summer 2007 when he was battling floods and foot-and-mouth disease, and failed to lay out a strategic vision.

Mandelson also said that Brown had too few heavy hitters in cabinet. His remarks were made before he himself returned to government.

The prime minister has often had to battle smears about his mental state. George Osborne, the shadow chancellor, once described him as “faintly autistic”.

Mandelson yesterday described himself as the cabinet’s “unifier” and insisted he had shed his old reputation as the “prince of darkness”.

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