Sales of Boris Johnson’s memoir, Unleashed, have slumped by 62% in its second week since publication.

The heavily marketed tome, promoted in a prolonged media round by the former prime minister in recent weeks, only just managed to cling on to the No 1 spot in the official UK Top 50 this week, selling 133 more copies than Tim Spector’s The Food for Life, according to Nielsen Bookscan’s Total Consumer Market data.

Unleashed covers Johnson’s time as London mayor, foreign secretary and in Downing Street, including his accounts of the Covid pandemic, Brexit and the 2019 general election.

It was the bestselling release of the week when it hit shelves, recording 42,528 sales, outselling David Cameron’s 2019 memoir For the Record, which sold 20,792 copies in the week it was published. Liz Truss only sold 2,228 copies of her memoir, Ten Years to Save the West, in its first week on sale earlier this year.

In a review for the Guardian, Martin Kettle said of Johnson’s book: “It is full of angry self-righteousness … Though Johnson likes to parade the outward signs of his intellect, there is not a philosophical sentence in the entire book.”

News of a lull in Johnson’s sales come after a YouGov poll found many Britons did not believe the claims he made in Unleashed.

Only a quarter of respondents thought Johnson’s claim that Buckingham Palace had asked him to try to convince Prince Harry not to leave the UK with his family was probably or definitely true; 46% thought it was probably or definitely false and 29% were unsure.

Just 31% thought his claim that Brexit meant the UK was able to get Covid vaccines faster than EU countries was probably or definitely true.