This is what 1500 years looks like - Borrowdale Yews

 

I found a lovely guide to ageing trees from their girth here. Sadly I didn't measure the girth of the Borrowdale Yews but Internet cheating here says 7.56m at present but previously larger. This would tie in with the implications of the "poor ground and some exposure" section of the first document. Not as accurate but easier than counting tree rings in my opinion!