In the spring, a plant appeared which I had certainly never sown or planted. Out of curiosity, I let it grow and flower. And I’m glad I did, as the flowers were most charming.
I didn’t have a name for it, but whilst reading Food from your forest garden by Crawford and Aitken I came across the very same. Columbine, or aquilegia vulgaris, is apparently edible. Or rather the flowers and leaves are (the seeds and roots are poisonous).
Now, I don’t know if my aquilegia is a true vulgaris or a hybrid, so I don’t in turn know if I really should be picking and eating the leaves (the flowers have sadly turned to seed). However, at least I now know what my mystery visitor is called.