History will judge Boris Johnson as one of the most damaging prime ministers in British history, Reform UK chairman Zia Yusuf has said. Yusuf told the BBC's Political Thinking podcast Johnson would not be welcome to join Reform UK. The Reform UK chairman criticised Johnson's record on the Covid pandemic, immigration and public spending when he was prime minister between 2019 and 2022. Yusuf said there was "nothing Conservative" about Johnson and branded the Tories an "extremely left-wing party" in government. The BBC has asked Johnson's spokesperson for comment.