Organizers said they have obtained guarantees from police they will not be arrested for the show of disrespect. Scotland Yard came under criticism for pre-emptively arresting several people in crowds watching the marriage of Prince William and Kate Middleton, The Independent said Monday.
"The police said they see no problem with this as long as it remains peaceful," organizer Rebecca Lush Blum said. "We'll be turning our backs as the funeral procession passes, for the multitude of different reasons we all harbor. If many people turn their backs it will be a deeply symbolic act, and a counter to all the revisionism and attempts to stifle dissent."
Thatcher, a staunch conservative Tory leader, was Britain's prime minister from 1979 to 1990. She died last week of a stroke at age 87.
British Prime Minister David Cameron, who now leads the conservatives, called the protests "disgraceful."