I have this cultivar growing in my GA garden and it has the black hips one would expect from a spinosissima cultivar.

The parentage given by Sheila Holmes is likely incorrect. I too was given the parentage directly from Robert Erskine (good friend of mine), and it was op Rosa altaica. I think it's likely the other parent was the native Rosa acicularis or R. woodsii, which would explain the pink tone of the flower. Note this cultivar supposedly has the same parentage as 'Beauty of Dropmore', but the flower form and colour of this cultivar is what one would expect from a Rosa altaica x R. spinosissima cross.