Thank you for your comments all, Hamadryad as it happens the next picture down is exactly that and was taken to show the Fungi, Rot, Orange Sap Rot (so I am told) all in the same picture. The Fungi itself is difficult to see at this size and resolution but is just below centre in the vertical and near the far right of the picture, the trestles were placed there by me as a means of protecting the Fungi the reason being the gardener has been knocking them over and disposing of them for a lot of years (10+) in and around this area to stop the 4 Daschunds living there from coming into contact with them just in case - I only became aware of this recently. The ground surrounding the base of the tree HAS NOT been altered except to say that a holly surrounding the tree was recently removed and I guess that the gentleman that did so raked the area to a reasonable level, that may have dropped the level but not by much if at all but certainly has not increased the level.
I did today have a Tree Officer inspect the tree and although the Fungi looks dark and shrivelled now he felt it was Collybia Fusipes, also we removed the soft bark and Orange Sap Rot that was present between the two buttresses leftmost on the same picture I previously mentioned - there was quite a lot of it and the officer felt that it was a root infection from the roots up to this point, also there is evidence of recent cracking between the tight bifurcation but the large limb is receiving support from a tie branch that has grown horizontally from a branch further up.
As a final point I did find today another Single specimen of Fungi about 12m from the tree and measuring about 15cm possibly a bit more in diameter across the top, this compared with the Collybia Fusipes looks smooth, well formed not messy and gnarly and I have included the pictures, they are not that great as they were taken using my phone and I took the pictures close up to get better detail when and if zooming in.
Again you knowledge and input are very gratefully received. Many Thanks
P.S. I will take a picture showing more context and of the whole tree and hopefully better pictures of the other Fungi.