There are over a dozen native species of Willowherb in Great Britain, and the one shown in these pictures from the Newport Wetlands is, as far as I can make out, Great Willowherb (Epilobium hirsutum). It was reaching almost head high in dense stands. I loved the way that access to many areas at this reserve has been made easy for all kinds of visitors, with main paths that were safe and suitable for less able walkers, families with pushchairs, and different kinds of wheelchair user, but also narrow mown passages winding through the vegetation so that you could get up close to see the details of Nature and really get a feel of the place.
Jessica's Nature Blog 