This flower I am not a hundred percent certain about the identification but I think it is Nipplewort (Lapsana communis). It certainly is a common yellow flowered plant and is not confined to this particular habitat in the strip of arable weeds that I have been investigating. There are so many similar yellow flowered plants that I am never absolutely certain what they are. Anyway, this is my best attempt. If you know better, please do let me know.
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