I have searched the gardening book for the name of this flower & I am pretty sure it is a Polgonum or Mountain Fleece-flower.
It is a perennial flower & it has a flush of these flowering spikes before dying off into a bit of a straggly mess & then having a second lot of flowers later in the year.
I think you can get a red variety too.
I am not a great photographer of flowers much preferring a good street picture or some thing with a bit of life to it but this is all I have to offer today !
I eventually found this plant in our gardening book, I see Fanny has already come up with the name , but have to add the variety we have is "Superbum" so you can guess what we call it lol