The extraordinary sight has shocked Britain. London Mayor Sadiq Khan also ordered another eight statues to be covered by protective casing while tensions are high. Those statues include tributes to Nelson Mandela,Mahatma Gandhi,George Washington,and the cenotaph near Downing Street.
In his strongest comments yet on the wave of demonstrations sweeping Britain in the wake of the death of African American George Floyd in police custody in Minnesota,a furious Johnson lashed the growing campaign to tear down statues of historic figures with links to racism or slavery.
"The statue of Winston Churchill in Parliament Square is a permanent reminder of his achievement in saving this country - and the whole of Europe - from a fascist and racist tyranny,"Johnson said on Friday.
"It is absurd and shameful that this national monument should today be at risk of attack by violent protesters."
Churchill has been credited as Britain's greatest prime minister following the defeat of Nazi Germany during World War II.However he also harboured racist attitudestowards Indians and Indigenous Australians,and his policies have been blamed for causing the Bengal famine of 1943 which killed up to three million people.
"Yes,he sometimes expressed opinions that were and are unacceptable to us today,but he was a hero,and he fully deserves his memorial,"Johnson said."We cannot now try to edit or censor our past. We cannot pretend to have a different history.