Confidence: It's likely to be this, but I can't be certain.
Notes: 2cm larva found at rest on heather, lots of bilberry in the area. It is a very good match for ukleps Clouded Drabs, especially the last 3 final instar pics. White dorsal stripe, yellow lateral stripe, a fine speckled white line half way between the 2 lines already mention, white spots along the side in the right places and white freckling all over the dorsal area. It is said to feed on a wide range of trees and shrubs.