Fern growing out of a crack in a wall.
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If I saw it again is there anything specific I could photograph (or photograph better!) to clarify the ID?
Books don't generally give descriptions for immature ferns, so you're dependent on finding someone who knows the species through its life cycle.
The shape of the base of the frond differs between the two species. If you could produce a non-foreshortened photograph of a whole frond it might clarify things.
Lat/Lng: 54.285, -0.4167
OS grid ref: TA031888