Oh No! - Not Another Fungus
This is probably an Amethyst Deceiver (Laccaria amethystea) It matched some images on the internet and not others, but there again the deceiver is a variable species.
The on-camera flash has made it a little redder than I remember it. I am certain it was slightly bluer.
I found it in mixed deciduous woodland between beech and sycamore trees.
[EDIT, Sunday 1pm]
As Runhills has pointed out (see below) I was mistaken with my initial ID on this.
Having reviewed it, I agree with his suggestion that it is in fact a Wood Blewit, Clitocybe nuda (also recognized as Lepista nuda and Tricholoma nudum), and I am happy to make that correction.