Last Monday (30th April) Greenpeace activists shut down the head offices of Centrica (the owners of British gas). The activists chose Centrica as a target because not only have they been solidly lobbying against renewable energy, but they've added an extra £100 per year to the average household elecricity bill.
Around 50 activists, some of them locked on, shut down their head offices- ceasing trading and admin work for the day. They delivered them huge gas bills in the form of massive placards that barricaded their doors, as well as pasting giant wallpaper bills on the walls. As a result their boss, Sam Laidlaw agreed to the talks that he had been resisting for weeks.
One protester was briefly accused of “attempted manslaughter” for chaining a door two foot away from another fire exit. Despite this there were no arrests.
For this more see Greenpeace's video:
http://www.greenpeace.org.uk/blog/climate/video-why-we-shut-centricas-office-20120430