Lord Razzall, his election chairman and chief strategist, has warned the Liberal Democrat leader that he must “boost the leadership questions” as he maps out his plan for the next four years.

He advises Mr Kennedy, who often appears lacklustre when making set-piece speeches, to plan a series of lectures to enhance his status and to improve his expertise in international affairs.

The analysis is set out in a six-page memorandum from Lord Razzall to Mr Kennedy reviewing the Lib Dems’ performance in the general election and mapping out plans for this Parliament. A copy has been obtained by The Times.

“We need to spend the next four years building you up as a future Prime Minister,” Lord Razzall writes. “You get extremely good ratings on honesty, trust, in touch with the needs of ordinary people.

“We need to boost the leadership questions — which I suspect must be done by a combination of big speeches, well trailed in the media, and the development of an international expertise commensurate with a potential Prime Minister.”

He further admits that the Lib Dems are not perceived by voters as strong enough in all parts of the country to be regarded as a national challenge. This, rather than policies such as local income tax, was the key reason why the party did not do better in the polls, Lord Razzall says.

This is in line with the analysis of Julian Ingram, the party’s pollster, who in a presentation to senior Lib Dems said that credibility had been the biggest obstacle to persuading voters that they could win. “There was an uncomfortable question of leadership which hovered in the background,” one of those present told The Times.

This polling suggested that the Lib Dems made a strategic blunder in targeting so much of their manifesto at pensioners, with policies such as free long-term care for the elderly and a citizen’s pension.

Voters over the age of 65 proved least likely to vote Lib Dem. Popularity was highest with the under-30s.

Lord Razzall suggests that many pensioners have negative impressions of Charles Kennedy’s party formed in previous generations when the Liberal Party was “not a serious player”. But he argues that the party achieved much greater recognition than in previous elections for its top policies, including a 50p top rate of income tax which was “extremely popular”.

This suggests that people close to Charles Kennedy may resist moves to drop the 50p tax band, which are being led by the party’s economics spokesman, Vince Cable.

On future plans, Lord Razzall says the party must start collecting money earlier in the electoral cycle and get pledges of “significant funding by Christmas”.

The Times has been told that Michael Brown, a City financier who gave £2.4million via his company to the Lib Dems weeks before the election, attended a post-election dinner, at which Mr Kennedy thanked donors, and indicated that he remained interested in helping the party.

Lord Razzall further advises that the Lib Dems need to develop a “narrative” to help voters to understand what they stand for, suggesting they should present themselves as the only alternative to Labour.

The Lib Dems also need a new “look”. “We must always be fresh, optimistic, go-getting, young, caring,” he says.

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1959: Born in Inverness. Educated in Fort William before studying politics, philosophy and English at Glasgow University

1983: Elected MP, then the youngest in the House. Holds a 14,249 majority in Ross, Skye and Lochaber seat

1999: Becomes leader after stints as party president, spokesperson on European, agriculture and rural affairs

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