Level 5 Goose Warning on the London Underground

I've seen plenty of wild things at the metro station before, but I've never seen a sign warning people about a "level 5 goose warning" like the one in this photo . The cautionary sign reads " Level 5 Goose Warning – The Goose on platform 2 is violent and has claimed the platform as his own – Please avoid". This is the best thing I've ever seen in the metro. Has a level 1-4 goose warning ever been issued? Exactly what kind of damage can a level 5 goose cause to humans? Well, I'm deeply terrified of geese, and if I saw this sign I would be steering clear from platform 2 by all means.