Group of Caterpillars removed from Primrose

Group of Caterpillars removed from Primrose

Observation - Group of Caterpillars removed from Primrose. Description: These caterpillars are found on the primroses and on the chives in the garden. They are only seen at night. Length is 20 to 30 mm. Can anyone advise on the species

These caterpillars are found on the primroses and on the chives in the garden. They are only seen at night. Length is 20 to 30 mm.

Can anyone advise on the species