This is a low-growing perennial which has flowers which at first seem to be smallish versions of Greater Stitchwort. These flowers (15-20mm across) are in small groups of 3-5 and have 5 spreading petals which are notched and twice as long as the sepals. There are 5 styles and 10 stamens. The leaves are in opposite pairs and join around the stem. They are narrow and softly downy. This is a mat-forming plant species which also sends up flowerless shoots. It flowers from April to August and is usually found on dry sandy soil, in grassy places and hedgebanks. It is a native species which belongs to the Caryophyllaceae or Campion family.
I first spotted this species while walking at the Flaggy Shore in the Burren in Co Clare. It was a very wet day in July and the flowers were absolutely sodden. I took the photographs that day but would prefer to do them justice on a drier day. Maybe next year.
If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre