Yes, it's a public bench, and they yarn-bombed surrounding lamp posts too. The two hams own a knitting shop nearby, so it was clearly a publicity exercise for them, and it worked because it got them a large feature in the local press.  I hate yarn bombing too, someone else did it in our churchyard recently. We have a beautiful 14th century church with a churchyard which is always stunning thanks to the council gardeners, and they thought fit to hang pompoms and other crap from all the trees.