Wild flower

Today was spent attacking he border I blipped a few days ago. It looks a bit bare now but at least it's better than it was, and I can get some new planting done. I took photos of some of the things I found, some of which were colourful but could hardly be said to be cute! This flower was growing out of a crack in a wall and I thought it looked attractive. I've no idea what it is but to put it in perspective, each of the petals is no more than two millimetres wide, and the leaves are quite fern-like.