The home secretary Yvette Cooper has faced intense criticism for choosing to proscribe PA, even from fellow Labour MPs like Clive Lewis, who warned the proscription “undermined democracy” and told parliament it risks “confusing dissent and terror”.

Organisers say unprecedented numbers will test the Metropolitan Police's pledge to arrest everyone supporting the banned group

The U.K. government has proscribed the network as a terrorist group, a decision fiercely contested by the group itself.