Flowers in my wall

In the white painted wall in my yard (soon to be repainted) there are, growing in cracks in the wall, some rather nice flowers. They're turning now, but I took this photo last week.

I don't know what they are (are they daisy family?), and I don't know how they collect nutrients, which must be limited in small cracks, or indeed how they collect water, to be able to grow. They seem to migrate along the wall, but how they achieve this is also unclear to me.

I have seen them before in the Mediterranean biome of the Eden Project in Cornwall, which I'm going to again soon. I will try and find out their name, and solve the mystery of their existence.