Growing in the garden, this is Great Willowherb, Epilobium hirsutum. It is, as the binomial suggests, very hairy. It has large flowers with a distinctive large creamy stigma with four lobes that arch backwards forming a cross.
Willowherbs are a family in their own right, but the family name is Onagraceae.
This is one of three posts needed to bring the blog up to speed, having been a bit slack at the end of October.
I have also noticed that I've blogged one species twice. A big money prize for anyone who spots which it is.