This seemed to be raised up into leaflets so I have described it as foliose. It was growing on a sandstone tombstone. It was definitely green and not one of the bright yellow ones.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
I shall inspect it again. I feel that it is more of a lichen than an algae but perhaps it harbours more algae than others so is greener. I'll try for another photo.
Lat/Lng: 53.0202, -2.7657
OS grid ref: SJ487472