Oenothera biennis. 

This is the evening primrose,

 Blooms open in the evening) so beloved by ladies with menstrual

tension issues. The whole plant is edible - roots are said to taste like

potato. The oil that is used medicinally comes from the seeds which are 24%

wv oil. although tasty and medically beneficial, in sensitive individuals it

can increase the likelihood of epileptic episodes.

 I found it just along the A259 outside the village.