Unfortunately, as I arrived they were taking the turf up, and so I didn't see the full effect. It did look good, though.
Around Hayward's Gallery, look up. There are statues on the rooftops, people just standing there. I'm sure that permission must have been asked from the police (phone calls from people who only spot the one thinking it's a suicide attempt). The installation is part of an Anthony 'fog in the box' Gormley collection.