Very interesting topic. I have a special place in my heart for trees, especially the Yews.

There are several dated Yew trees around Britain (mostly in church yards) that are older than 2000 years old. One is at a church yard in Ulcombe in Kent. (Locals say the older of the two really old ones there is closer to 4000 years old...)

There are 20 to 30 yews at Kingly Vale (at a guess-- I've never counted them because I'm always too awestruck to remember to). It's a national heritage site near Chichester in West Sussex (?). I don't know their age but some must be over a thousand easily. I've always thought they were Tolkien's inspiration- they are very sentient trees!!! and the three (Neolithic?) burial mounds on the hill overlooking them are also worth a visit.

I'm always surprised that so few English seem to know about the place, it is incredibly awe-inspiring to be in that grove of ancient beings...
Certainly one of the most magical places in the Isles.