Cuckoo Flower or Ladies Smock as some may know it. This one has its own cuckoo spit [contains the nymph of the froghopper so dear old google tells me] but it derives its name from appearing at the same time as the first call of the cuckoo.
This I find is Hawthorn or May Flower. I had always thought them to be white or a very pale pink. Having identified it I'm now seeing it in lots of the hedgerows so not sure whether it's the same species of Hawthorn or not. If anyone can enlighten me I would be most pleased! I slog past this on my "running" route...it gives me something to aim for as a marker on my second lap round.