Found on a watering can pressed against a wall it was probably warming up after a few months of sluggish activity. If the weather continues to improve it will resume feeding and growing before pupating in a cocoon spun on a plant or in leaf litter.
More information on the eye catching Scarlet Tiger moths that will emerge in June/July can be seen on the link.
Many thanks to Joe for sending in the image shown right.
Other caterpillars sighted recently include those of Fox Moth, Drinker, Oak Eggar, Ruby Tiger, Square-spot rustic, Lesser Yellow Underwing, Angle Shades, Light Brown Apple moth and two nettle wrapped micro moth caterpillars which will have to be reared through to be certain of identity.