I saw this flower on the edge of the reed beds and it struck me as rather unusual.
One of my friends Graham Barker, far more in touch with plants than I, was able to identify it as '' Redshank '' ( aka Willow weed and Lady's thumb ) a member of the Knotweed family.
It is invasive but can be controlled when required.
What a shame that such a striking flower is a weed.
NB Another friend, Eric Graham has also suggested that it is '' amphibious bistort '', a species that Graham and I also considered.
Its not for me to play King Soloman when it comes to plant identification so its good to have two nominations.
My original position continues to be that it is an unusual looking flower !.