Insubstantial, small fern growing on steep and vertical surfaces in the presence of dripping water.
No interactions present.
Probably go with Wilson's. I visited Shaugh bridge in the late 70s and think I saw both filmy ferns
Then I shall have to return as I would like to bag H. tunbrigense as well. Thanks for the detail.
Lat/Lng: 50.4543, -4.0677
OS grid ref: SX533636
Alongside the River Plym.