Caterpillar ID

Caterpillar ID

Observation - Caterpillar ID. Description: This was taken at Slimbridge, I almost stood on it. Ive searched through my wildlife books butcant find what type it is. Can anone help

This was taken at Slimbridge, I almost stood on it. Ive searched through my wildlife books butcant find what type it is. Can anone help