Growing in muddy ditch close to River Lagan.
No interactions present.
Apparently it does occur in NI: "Mainly in shady damp woods about Lough Neagh and along some of the waterways connecting with it. Also common near Belfast along the Lagan." (Flora of Northern Ireland website)
Good! Its a lovely plant!
Lat/Lng: 54.5644, -5.9311
OS grid ref: NW459259