...for Gwernvale is c3900BC, and not 4,400BC.

Breconshire only has court tombs, we have no portals, dolmens, etc.

They are all (pretty much) in one location: The Black Mountains in various river valleys, many intervisible. On both sides of the England/Wales border.

One, Ty Illtyd (Illtyd's House) stands alone 4 or so miles west of The Black Mountains group, and that's yer lot, with a "possible" other 6 or so miles to the NW of it.

Most are, with variation lateral, with a couple of terminal, but no transepted (ie. West Kennett), think more of Belas Knap with the blind false entrance and tombs arranged in pairs along the side, sometimes with a larger main central chamber.

Ty Isaf (Low House?) is interesting in that its forecourt horns were added after it was already in use as a tomb.

...otherwises yer standard horned blind lateral with a cairn of stones. Clyro and the English ones are/were chambered long barrows instead of chambered long cairns.

Royal Commission For Ancient and Historical Monuments in Wales always refers to them as "Irish stylee Court Tombs".