Unfortunately, protests like this only tend to entrench people's pre-existing views, and in some ways may serve as a disincentive to action.
Basically, and I know I'm personally as guilty of this as the next person, people want their every-increasing consumerist quality of life above all else, and while they quite like the idea of a cleaner, less-fukced planet, they'd rather have their personal guilt assuaged by tickling around the edges than actually grasp the nettle and accept that their fundamental values have to change in order to make a meaningful impact.
Want three foreign holidays a year? Want to eat red meat seven days a week? Want to spend your weekends using pointless retail as a leisure activity? Sure, crack on with all that, so long as you make the right noises, forego plastic straws and sign the odd petition for somebody else to sort the problem. You too can feel smug as fukc as you drop half a dozen bottles off for recycling out of the back of your 3-ton SUV.
At the very very heart of the problem is that reducing environmental damage and increasing national wealth are directly contradictory objectives - tax polluting companies and they move to china, tax car production and people lose jobs, tax imported food and people's grocery bill goes up, tax road travel and people complain that their real wages have fallen due to increased commuting costs. As a nation, we are a million miles from saying "yes, I'm willing to forego more trinkets and baubles to save some animals I'm never going to see or protect a forest that won't even be planted until long after I'm dead".
And TV images of crusties being dragged away by the cops doesn't do much to sell the kind of fundamental lifestyle and value change that's needed. The sub-conscious messages are that environmentalism is extreme (so the little concessions you makes are a *fair* compromise), that taking any positive steps makes you more like those smelly people you hate (and more importantly, look down on), and that ultimately, it's all a bit pointless anyway.
If change is going to happen, it has to happen *within* the realm of established social and political norms. I hate to say it, but those pushing for change need to learn a lesson from the UKIP playbook - sell an idea that genuinely speaks to people's fears and desires, convert the support of the people you persuade into ballot box numbers, and scare mainstream political parties into incorporating the narrative into their own ideologies.