Found on very wet area of ground below coastal path and above stony beach.
No interactions present.
Many thanks for the ID - have agreed it - will update the title accordingly.
You're probably right with the ID, but I wonder if it could be Epilobium brunnescens. It would be good to rule it out.
...I've being trying to think of it since this was posted. I think you could be right!
I think the Epilobium is more associated with upland habitats and is not usually coastal. A photo of the underside of the leaves would resolve the issue. The Anagallis has a dark line round the edge of the leaf.
Sorry, didn't have time to photograph the underside, as I usually try to do, on this observation. If I am "in the neighbourhood" again in the not too distant future, will try to update it - many thanks for all your pointers. John
Lat/Lng: 51.4936, -3.7299
OS grid ref: SS800786