Organizers had commandeered a vintage open-top red London bus for the rally, installing DJ decks to blast out music and swear word-filled speeches from Johnson critics.
Protesters chanting expletive-laden slogans eventually converged on Downing Street, which was temporarily placed under lockdown – disrupting cabinet members coming and going through the evening to learn of their new roles, AFP reported.
Images of the scene showed plumes of blue and pink smoke from flares lit by demonstrators rising above the crowds.
“I’m here to protest against Boris Johnson’s policies,” Andy Unger, a university professor in London, said as the youthful crowd cheered various addresses by activists.
“We’ve gone into an age in politics where facts don’t matter and Johnson has been spectacularly successful in exploiting that.
“I just don’t think he’s the right person to be prime minister – he’s not my prime minister,” he added.
Attendees, holding an array of placards – emblazoned with slogans like “kick Johnson out!” and “wake me up from this nightmare” – marched to Westminster after first rallying in Russell Square by the University of London campus.
The “street festival” demonstration was supported by various progressive groups, including Momentum, the left-wing campaign organization closely aligned with the main opposition Labour Party.
They said up to 10,000 people had attended the protest.
Shadow finance minister John McDonnell was among those to address the crowds.
“Do not fall for this buffoonery: Boris Johnson is dangerous,” he warned, in reference to the new premier’s trademark bombastic style.
“He’s dangerous for our communities, he’s dangerous for our society, he’s dangerous for the rest of Europe and our globe as well.”
Valentina Frasca, of south London, was another to turn out with family members.
“I dislike Boris a lot,” said the 37-year-old teacher.
“He’s a racist and a xenophobe, he’s a liar, he’s not a leader.
“I know how Americans feel now – I feel quite embarrassed,” she added, in reference to those similarly opposed to US President Donald Trump.
