Greater Sea-Spurrey (Spergularia media)
Although the 'Greater' Sea-spurrey it is a small flower, usually white but it can also be pale bluish/pink.
It is a common flower of the coast, it loves salty conditions and it can also be found inland along the side of roads that are frequently salted in the winter months.
This is also known as the Greater Sand-spurrey in some books which can be confusing. There is a Lesser Sea-spurrey which is less common but the flowers of that are always pink.