Boris Johnson has revealed the exact date for an “unrestrained” memoir on his Downing Street days. The ex-Prime Minister’s book, titled Unleashed, is being published by William Collins on October 10. Harper will release his memoir in the United States, the nation of his birth, just five days later. Unleashed will cover pivotal moments in Johnson’s political career, including his stint as London Mayor and the Brexit wars before and during his premiership. Johnson led the Tories to win the 2019 General Election with a majority of 80 seats. He later led the UK through the coronavirus pandemic and…