We've spotted a few of these skeletal monarchs round London lately. The one on the left is in Smithfield, the one on the right is down Hanbury Street and the one below sits on Clerkenwell Road (the Latin motto reads: Canis Servo Regina; Dog Save The Quees).
The design is by D*Face, one of London's most prolific and inventive street artists. You'll have seen his work all over the place, usually featuring things with wings. But here, the trademark flappers have decayed to bone.
Let us know if you've seen further examples.