[hamadryad]

Apart from two things it looks like Dryadeus, the colour form and guttation gives me that idea.

however it may well turn out to be inonotus radiatus, I suspect this because of the number of brackets and that the substrate appears to be birch, though possibly mountain ash (Sorbus)

If its Dryadeus, and on birch it would make for an interesting record, if radiatus its going to be a fine example.

but I could be wrong on both counts, though I am pretty confidant its going to be the radiatus

I have decided it has the wrong colour guttation for radiatus, Cuticularis is more likely. I love going back to emergents over a period of days to see what they become!