Growing at the foot of a garden wall and edge of a pavement. Perhaps a garden escape.
No interactions present.
Thanks for the agreements, but I have hit a snag. Keeled Cornsalad (V. carinata) apparently is a frequent garden weed in Weston - probably more so than locusta. I don't think the 2 species can be separated other than by the seeds?
To address the snag, put up an ID as Valerianella sp., and hope that it garners the requisite agreements.
Or perhaps Chris or Graeme can offer a reason for identifying it as V. locusta.
Lat/Lng: 51.3558, -2.9891
OS grid ref: ST312623