First stop Narberth, for some (veggie) treats.
Then a 60 mile drive around the top of the western Brecon Beacons.
I wanted to go and see it. I had to go and see it! And so did my friend, Cheryl. We started to make plans.
So when I saw that our detour home would take us through nearby Sennybridge, I had to go there for her, as well as for myself.
The tree is so old it has split into two halves, one 40 feet wide, the other 20. For a long time it was thought to be two trees, but tree DNA says otherwise.
In a pamphlet in the church, yew tree historian Allen Meredith writes that 'walking trees' occur as part of a natural layering process, or can sometimes be due to lightning strike or other natural phenomena. Thus part of the tree can appear to move away from its original site.
Both parts of the tree can continue to produce new growth to cover the old and decayed wood, and eventually it will appear as two individual trees.
The researchers obtained several samples of old wood from the larger trunk, where over 120 rings were found in one and a half inches, making the Defynnog yew a very ancient tree - a sapling in the early Bronze Age.
It was the perfect place to contemplate life and death and regeneration.
I get the feeling that this tree, like the other remarkable trees I've met, is quite aware of how special it is.
St Cynog, son of Brychan, was an early British saint and martyr, and the yew is not the only ancient thing associated with his church here.
This is a Romano-Celtic gravestone with the Latin inscription RUGNIATIO LIVENDONI, meaning [the stone] of Rugniatis, son of Vendonius. It's believed to date from the fifth century, and was discovered in 1853, built into the external face of the church tower.
On the left hand side are vestiges of Ogham script which are no longer legible, thanks to the mediaeval masons who fitted it into the tower ...
... and at the top, Celtic inscriptions from the ninth to 11th centuries.
Also very very old indeed is this stone holy water stoup, believed to be pre-Norman ...
The base is also a font which has been upturned.
On the rim is carved SIWURD and GWLMER, which apparently indicates a Viking settlement in the early 11th century.
This interested me on account of Sywardes Cross (aka Nun's Cross) on Dartmoor, which features large in my novel, 'Dart'.
However, Syward/Siward of the Cross has been tentatively identified as the 11th century Earl Siward of Northumbria. This Siwurd could be Richard Siward, Lord of Talyfan, who lived two centuries later.
It was time to be going, however.
One last look at the churchyard, bright with fox and cubs ...
... and we headed home at the end of our West Wales adventure.