I live in central London and there are protests pretty much daily about all sorts of things. The problem is more no one paying attention to them rather than their being illegal.
I don't support that organisation, but I support the right not to be banned from walking in protest, in a pre policing move.
You can bet the static protest people will be kettled too as a defensive measure. I don't support frightening makeshift imprisonment in the street.
I don't support the requirement to get permission from the police to walk in protest either
Tell me: how much change you think you can effect with a few people stood static, self policing your words as not to cause offence to anyone, and then likely kettled by the police? Tell me that isn't banning protest
You're basically permitted to stand silent with a totally inoffensive sign (offensive or potentially to absolutely nobody) in a very small group that attracts no attention