There are quite a few variations of deadly fungi in the UK. The most deadly, I believe, is a close relative of Amanita phalloides (Death Cap), known as the Destroying Angel( Amanita virosa). The Amanita muscaria that Richard refers to is the Fly agaric (rheindeer eat them then the Laplanders drink the rheindeer urin and thats how you get flying rheindeer)or so I'm told.

Ebbie, if your fungus is not either of those I suggested, I think maybe it's not a Clavarias (club fungus) but a type of Stinkhorn (related to clavarius I think). Try this link Phallus rubicundus