Growing between the pavement and a wall. The closest plant I could match it with is Mexican Fleabane?
No interactions present.
I think you should post an ID Jon. I'd rather agree to your ID for Mexican fleabane than steal your glory. Edit: it's too late now.
I edited the observation title instead! Everything looked right except the leaves didn't match the illustration in Francis Rose (The Wildflower Key)
Lat/Lng: 51.47265, -2.63189
OS grid ref: ST562750