This species, whilst called sulphur polypore (Laetiporus sulphureus), is better known 'in the trade' as the chicken of the woods. Why? I have been unable to find out why, it does not appera to be because it has the taste of chicken when cooked so presumably it is something to do with its appearance. Depending on its age it can be a yellowish colour later becoming more brown and it tends to form in layers of brackets so forming what looks like a much larger body. In north America this is considered a delicacy and so I suspect the name originates from there.
This is a common species appearing from spring right through until the autumn on broadleaved trees, especially oak and beech, and is paraasitic and will kill its host forming a dark brown rot inside the trunk of the decaying tree. It also appears on yew and because yew is poisonous it is thought that the fungus could be poisonous if taken from there and is best left alone.
Best eaten when young according to my book so as I am not young any more I will leave it be.