I found this abundance of what I believe to be Pleurotus ostreatus Oyster mushroom this morning. The tree was dead and the fungi had completely taken over the whole trunk. Took all angles and underneath for J @Frog.
Wow what a huge colony! This is either a Trametes (turkey tail) or a mixture of Trametes and a similar looking bracket e.g. Stereum: The underside is the main key.
Thankyou again J, it covered the 30ft tree amazing to see, glad I managed to get the underside for you to ID.