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I do not think it is Saxifraga granulata (Meadow Saxifrage). We have lots of it in our garden. It is a distinct meadow species growing up to about 40 cm with showy flowers. The white petals without any coloured dots would match; however, they are about 1,5 cm long and have more that three veins. Your small flowers have three-veined petals.
S. granulata prefers sandy soil and does not colonize rocks. Here is a good description: "In late spring, meadow saxifrage produces clusters of large, star-shaped, white flowers with prominent yellow stamens.The loosely-branched, reddish, hairy flower stems emerge from a basal rosette. The leaves become narrower further up the stem. The plant overwinters entirely from bulbils housed in the axils of the long-stalked, kidney-shaped leaves, which form a basal rosette. This is a plant of old grassland and should be grown on moist but well-drained soil. It is suitable for naturalising in grass." The mentioned bulbils are very typical - dig out a plant and search for them. I am quite sure there will be none.