Himalayan Balsam

AKA Jumping Jack, Policeman's Helmet or to give it its Kennel Club name: Impatiens Glandulifera - few! Thank goodness for Google.

There's loads of this along the riverbank. This is an aggressive invasive non-native species. It was introduced to the UK in 1839 (thanks Wikipedia) at the same time as Japanese Knotweed. They grow so successfully that they don't give the indigenous plant life a chance. The Germans are apparently developing ways to convert the flowers into food.

Any road up, they're really pretty.