Tree fungus

Spotted this spectacular fungus growing on a tree while out dog walking. Due to having my four legged friend's lead in one hand and camera in the other, and this being above my head, it was a challenge to get a good look.
Anyone know what it is?

Apart from this, Friday 13th was a rather splendid day with an excellent lunch with my bestest friends, and a pleasant evening binge watching Jackson Brodie with my other half!