Trichaptum is plausible. From the photos I can't tell if the underside has pores. Some areas in the photo suggest that, but it's not clear enough to say one way or the other.
Would another photo help? I pulled another piece off from lower down - to my untrained eye the bottom looks similar in texture to the top (but cleaner).
If you look at the underside with a magnifying glass, is it still smooth or is the underside packed with numerous small holes? If with holes then Trichaptum. If smooth, then it could be Chondrostereum purpureum or (probably less likely) a species of Amylostereum. If you were able to bring a sample to the botanic gardens I could check it out. If you do so, please bring a piece at least several centimetres long, ideally still attached to a bit of wood. That ensures that the sample contains everything. When I collect something like this I use a knife (or hammer & chisel if the wood is hard) to get out a sliver of wood with the fungus.