Anagallis tenella Bog Pimpernel C DD N
I always used to see this in inland boggy areas until I went to the dunes in midsummer where it flourishes in huge carpets in the slacks. It can vary in colour from quite pronounced pink to a faint pinky white. The prominent leaves in the photo belong to Marsh Pennywort (Hydrocotyle vulgaris) not Bog Pimpernel (Anagallis tenella)
This plant has a western bias being prevalent in western Wales, Ireland and Scotland but absent from large parts of inland Scotland.