Do such demos make any difference? Is there any point, when our government seems to be one of the few that is doing anything constructive - surely it is the US or Italy or Russia that needs kicking in to action?
And the simple answer is, the more we do, the more we change things. Peacefully, rather than through the violent riots that kicked off in Germany around the same time as our rally and largely drowned it out. Furthermore, I think that getting churches to engage with campaigning makes a difference - it has more than a hint of the Old Testament prophets who challenged kings and rulers to do right by the poor. It also gets a group naturally inclined towards activism of one kind or another actively seeking to change the world. Wake the sleeping giant and see what happens.
And finally, it is church groups, more than any other single network, that are out there caring for the poor throughout the world, so if any group has a right to speak out, it is the church.