Growing close to an upland stream/flush in very damp soil.
No interactions present.
I clicked "certain as can be" but it got changed somehow.
I will pop back and see if I can catch it flowering in a couple of weeks - any excuse for a decent walk.
Oh and yes, beck would be right (although it was probably small enough to be called a 'gutter'.
Lat/Lng: 54.496934, -2.768818
OS grid ref: NY503115