Unknown moth

Unknown moth

Observation - Unknown moth. Description: Seen in mid-afternoon on a white umbel flower in a hedgerow beside a country lane, close to woodland. Length approx 20mm. I've looked in several field guides but have failed to pick out this moth. Help, please!

Seen in mid-afternoon on a white umbel flower in a hedgerow beside a country lane, close to woodland. Length approx 20mm. I've looked in several field guides but have failed to pick out this moth. Help, please!