You think police should ignore situations in which violence and destruction of property are highly likely?

Why? How does that benefit society?

At what point do you allow intervention? After they've destroyed £x,000 of property? After people are assaulted? How are you proposing police get deployed safely in those circumstances with 10s of thousands of protesters/rioters in the streets?

Don't you think maintaining law& order is a necessary activity of the state in a democracy?

You can't seriously think we should stand back and give over or streets to whoever can be most violent?