The pale mauve, thin-stemmed bell-like flowers of the Harebell (Campanula rotundifolia) are a lot tougher than they look. This little tumble of bells was growing in the corner of a wall in the ruined nave of Bolton Priory. The plants like dry, thin, poor soil so they can successfully colonise old walls. They look rather pretty, nodding in the breeze. They were one of my mum's favourite flowers and I have a bone china mug decorated with them, that reminds me of her every time I use it.
PS: Just read your comments.... OK, Betsy - here you are.... isn't it sweet?