I second that.
On the positive side, I've found that as Kathleen Harrop gets older it blooms more and mildew seems to trouble it less. You don't get a repeat of the speccy spring flush, but can usually find a few blooms, especially if it's deadheaded or trimmed occasionally. My KH doesn't come down with the milge as often or as badly as ZD. (Warm, temperate climate, dry summers, rain in winter, very few frosts)
It's a very lovely and versatile rose and the fragrance is sublime.
At a local nursery, two plants of this rose are grown on an arch that spans a path 2 - 3 metres wide and it's pruned for maximum effect in the spring. I suspect they sell huge numbers of KH when it's in full bloom.
A friend grows this more informally on the verandah posts of their home and their plants are very healthy and are rarely without some bloom. It handles the partial shade well, I've yet to see mildew on these plants and the thornlessness and fragrance are appreciated so close to the door of their house.