I'd be interested in knowing what happened to my scabious "butterfly blue" this summer.

The "foliage fading" is a clue - it looks as if the plants died back, and you've had to wait for new growth from the base when conditions improved. Not enough watering earlier on, when we had the hot spell? At least, that's what it looks like.

I have to say that looks suspiciously like a bad case of mildew. This variety is notoriously prone and this is a bad year for mildew on many plants.

I wondered whether to mention mildew Fractal - but I assumed Mondeoman would have mentioned grey mould - perhaps wrongly!

I have never seen this problem before and from my height of over 6' it just looked like the foliage was faded and discoloured. However, very close inspection indicates that it is likely to be mildew, although not like the mildew which attacked one of my roses a few years back. Thanks for your helpful comments and I will address the problem.