Found on cliff-top path. Very windy day, so photos of flowers not as sharp as I would have liked - proved impossible to get enough light whilst shielding them from wind.
No interactions present.
From the size of the leaves and habitat, I would go for binervosum agg. (Perhaps L. procerum in that location). L. vulgare should be in saltmarsh.
Many thanks cicuta58 for your feedback. Having read further into the 2 alternative species and viewed other web-site pictures, I think that Procerum is more likely in the cliff-top environment, as you suggest. Have therefore changed the identification
Lat/Lng: 51.3984, -3.5107
OS grid ref: SS950676