As I understand it 5-spot and 6-spot have short body hairs, but the caterpillar below has what I would say long body hairs, which would make that Narrow-bordered 5-spot Burnet. Which is a species we have not recorded in the Llynfi Valley. the plant leaf is Yellow Iris and it looked like it was attaching itself to the leaf getting ready to pupate. The area is well away from the site where I record 5-spot, 6-spot regularly as adults. Thoughts welcome.