Check it out:
This is described as the standard British work, covering 450 species including all of the common ones and many rare ones too.
This fills a previously very empty hole in my wildlife library, since I had no way to effectively identify lichen species. The book has a key, a large number of pictures and very usefully distribution maps for all species. I'm looking forward to using to add to my species list.
First species I need to identify is this one:
This was taken on our front wall using the MP65mm macro lens at about 4:1. The little cups are about 0.4 mm across!