Dusky Sallow? - ID help please

 Dusky Sallow? - ID help please

Observation - Dusky Sallow? - ID help please. Description: Quite a large white moth with several tones of brown zig-zag markings. 'Hairy' head and neck. Spotted feeding on knap weed on the South Downs. I thought it might be a Dusky Sallow but the markings don't seem quite right.

Quite a large white moth with several tones of brown zig-zag markings. 'Hairy' head and neck. Spotted feeding on knap weed on the South Downs. I thought it might be a Dusky Sallow but the markings don't seem quite right.