Yet again I thought.. "this should be an easy ID", and of course it turned out to be more challenging than that.
The best match I get is Blackfoot Polypore -
Polyporus leptocephalus but it does appear to be lacking the typical "Black Foot"
I have seen
Polyporus tuberaster growing close by to this area, but I'm not convinced it's an immature specimen as the pore spacing is larger in
Polyporus tuberaster
Size: 30mm
Smell: pleasant, mushroomy, "eat me"
Substrate: trunk of decaying dead tree, in mixed woodland
Your thoughts and comments welcomed.