Christopher, not sure of the varieties of mine.They are great plants for the Autumn- no staking needed! Try smelling them too.
The burgundy leaved one is the youngest. It may be in a slightly too dry a spot, but shall keep a watch & ensure well mulched. Can always move it if it continues to struggle a bit. The big original one I definitely moved when the adjacent trees encroached & dried things out.
That shot from Harlow Carr really shows what can be done when you have space & several plants.
Am sure I got both of mine from RHS shows as small plants. So anybody going to Malvern this next week may find them. Otherwise I know that they have been spotted at Tatton. More a decent herbaceous plant nursery type of plant rather than GC, although have seen them at one near us- at a price! RHS gardens too may have them. J.