BRIDEWORT : Spiraea salicifolia
Also known as willow-leaved meadowsweet, spice hardhack, or Aaron's beard.
Wiki tells us that it is a species of flowering plant in the family Rosaceae. A shrub, it is native to east-central Europe, Kazakhstan, all of Siberia, the Russian Far East, Mongolia, northern China, Korea, and Japan, and it has been widely introduced to the rest of Europe and to eastern North America. It has been cultivated since the 1500s for hedges and similar applications, but is not particularly well-behaved.
NatureSpot goes on to say that there are many similar species and hybrids, mostly with leaves hairy or tomentose on the underside, and the true species is now very rare and over-recorded. This a warning that we may have this wrongly identified here, but if so, it is likely to be a hybrid rather than a different species.
A bridewort shrub in flower on the upper Leven towpath, complete with visiting hoverfly, in late July.
NATURE SPOT: https://www.naturespot.org.uk/species/bridewort