Former cabinet minister Lord Mandelson has said that Labour could have won the 2015 general election but failed to do so because of Ed Miliband’s “insipid gesture politics” and his “vainglorious project”.

In a review for The Independent on Sunday of Philip Cowley and Dennis Kavanagh’s The British General Election of 2015 – the definitive academic account of the contest – Lord Mandelson writes that “Labour could have replaced the Tories in 2015”. He quotes the findings of Labour’s own pollsters, reported in the book, that voters were unclear about Mr Miliband’s policy and vision.

“It was not that he was too radical or left wing; if anything, his vague policies and insipid gesture politics simply left the voters not knowing what he was,” Lord Mandelson writes. “Nor was it that he was too anti-business; the public are not in love with big business but they do expect a prospective prime minister to understand the fundamentals of the market economy.”

The Labour peer, who began his political career as Labour’s director of communications in 1985, says “these problems could all have been put right” but it would have required “the sort of concerted, disciplined, strategic policy-making and communications that Cameron and Osborne excelled in”.

He praises the “quality of the Tory election team, including their external Australian and American advisers”. Lynton Crosby, the Australian consultant who headed the Conservative campaign, received a knighthood in the New Year Honours list last week. The Conservatives were also advised by Mark Textor, Sir Lynton’s business partner and opinion pollster, and by Jim Messina, an American consultant who was Barack Obama’s campaign manager in 2012.

By contrast, Lord Mandelson is scathing about Mr Miliband’s decision to hire David Axelrod, chief strategist of the 2008 Obama campaign: “While Labour was spending scarce cash on American-imported ‘message development’, the Conservatives were investing in detailed voter profiling and highly targeted message delivery.”

Lord Mandelson was one of the architects of New Labour. He uses his review to point out that last year’s election was the first since 1983 in which he “played no role whatsoever at national level”. Mr Miliband did not want him, he says, because “a desire to bury New Labour” was “at the heart of [his] being”.