What is it please?

A grey day again, such a contrast to yesterday. I thought this beautiful flower was a change from a daffodil and is lovely and bright.

Our 82 year old neighbours tell me they regard these flowers as pornographic!!
The mind boggles. Although last year, one day, I knocked at their door and it was a while before the husband came to open it in his white robe to say: "sorry it took a while Bob, we were in the bath" !! You have to admire them.

We have loads of them growing along the river bank, but I've forgotten what they are. All suggestions gratefully received:)

I hope everyone has had a lovely weekend, I intend to catch up with journals tonight having had a day off!!