Not going to try myself as totally unsure. My favourite is Oxalis because of no ring markings. Large patches amongst grasses.
No interactions present.
My money is on an Oxalis. It won't be a native but one of the garden escapes - perhaps Oxalis articulata, which has pink flowers
Lat/Lng: 51.3822, 1.3239
OS grid ref: TR313700
chalk cliff top