Yes - I accept that the yew is very special and has attracted all manner of magic and legends. I love them and have compiled a photographic log of all the really ancient ones that I have found. Nice pic of the Alton Prior yew over on the Portal.
My only reason for pointing out an alternative reason for the survival of ancient churchyard yews is to say that one old yew doesn't prove a pagan site. I do accept that it is a possible indicator though - just not proof.
PS - anyone had a good look at the sarsen quoins of Alton Barns just next door? Saxon long and short work, but out of all proportion - massive. Re-used and dressed?