It looks like Laetiporus sulphureus and is normally found on Oak and occasionally other tree species. It stains the dead rotten heartwood red.

If you have a large tree in your garden with this, then the heart wood is starting to rot.

Thank you, I have not seen the likes before, only bracket, toadstool/mushroom types & some very small stuff on rotting timber. Oh, & a very large puffball

It probably got into the tree from the wound caused by the farmer/land owner hammering nails into the trunk to use as a free fence post!

Few people realize how damaging this is to the tree!