Took this a few days ago, with the intention of identifying the caterpillar when I returned home, but didnt get around to it. This evening BBC Countryfile programme featured ragwort, and this caterpillar that feeds on it. It is a cinnabar caterpillar, which if it is lucky pupates into an attractive red patterned moth, but if unlucky becomes the host of an Ichneumon wasp larva, which develops from an egg laid in the caterpillar. Thank you Countryfile!
Yes we watched that programme too, fascinating, and a wonderful capture of the cinnabar moth caterpillar. Deserving of the Countryfile calendar I think!