Hello Beany. Dove has identified the plant correctly and I THINK I also see a stem of bindweed twining up the Balsam - another pernicious weed that can become invasive if not checked
Cacoethes: An irresistible urge to do something inadvisable
Unfortunately, waterways are just the kind of place they like to colonise @Beany1971, and they can cause major problems. The bindweed can look very pretty, especially in flower, but it's a menace too!
It's a place where beautiful isn't enough of a word....
I live in west central Scotland - not where that photo is...
Posts
an extremely invasive plant which causes many problems to wildlife habitat in the UK.
More info here https://www.plantlife.org.uk/uk/discover-wild-plants-nature/plant-fungi-species/himalayan-balsam
The bindweed can look very pretty, especially in flower, but it's a menace too!
I live in west central Scotland - not where that photo is...