This isn't a scientific study of the Lichens of Skokholm. Nor a comprehensive field guide.
It is a photographic guide of some of the lichens that you may enjoy seeing and learning a little more about.
They are grouped roughly by location. The landing in South Haven. Around the Farmhouse. The cliff path. And so on.
And if things don't fit neatly into that route then never mind. You may still see lichens to please you as you wander the island in the pages of this book.