Nasty visitor

This scary fungus has grown to this size in less than two weeks. It is at the foot of a huge beech tree near the entrance to our garden. The tree is a feature of not only our property but of the whole road. It is on our neighbour's land so he has sought advice. He has been told it is bracket fungus which will weaken the tree and eventually kill it. I looked it up on the RHS website and it does sound bad. With the current high winds the whole scenario is a bit nerve wracking!
The wind is strong but not cold, and the sun is shining in our south-east corner of England. Sorry for everyone further north - your forecast is not good.