Not a pretty sight

I spied this rather unappealing caterpillar in the hedge. So was delighted to discover (with the help of others) that this solitary creature was a purple hairsteak caterpillar. Not what I expected, although obvious similarities, it was the wrong colour. But like so many varieties they alter during different instars.

Very confusing! They prefer oak leaves yet here it was in a hedge mainly of hawthorn. A return journey; oak trees discovered behind – never noticing these young trees despite regular visits over the years. That is what you call focusing to the obliteration of all else (me insect hunting).