Very local in Britain; like a small, straggly Herb-robert. Confirmed by John Poland.
No interactions present.
Nice record. Not one I'm familiar with but the yellow anthers are a useful character and clear in your photo.
Biodiversity Officer - Shropshire
Thanks - for this one, I'm lucky to be right down south!
Lat/Lng: 50.8, -1.4
OS grid ref: SU4802