The green alkanet, evergreen bugloss or alkanet, usually found in damp or shaded places and often close to buildings. It has brilliant blue flowers, and retains its green leaves through the winter. It will grow where little else will, and the flowers are pretty and come in a long succession from spring to Autumn: if you hack it back to the ground it will return, unperturbed. Finally, and most importantly, the flowers are popular with pollinators.
Often this species needs to be planted just before the frost or needs a long period of cold for Stratification, so its seed dormancy can be overcome.