The last time a demonstration changed actual policy that I can remember is the Poll Tax strikes.
If everybody who wants to stop illegal immigration stopped paying their council tax, most of the councils would be immobilised.
The government would 100% have to step in then.
@RupertLowe10 I worked at an asylum hotel. They put their name down on one day and the doctor comes the next or they are carted off in a tax payer funded taxi