This lovely cheerful flower is Helenium ‘The Bishop’, commonly called Sneezeweed.
I grew this spurge from seed quite a few years ago and although the label has long since disappeared, I am pretty certain it is called Euphorbia cyparissias. I love its long season of interest, starting in the spring with the fresh lime green foliage, followed by the acid yellow bracts which age to red. In the autumn the foliage turns a lovely pink colour before dying back for the winter.
I purchased this Helianthus from an NGS Open Garden earlier this year. It is a perennial version of the popular annual sunflower and I have been surprised just how vigorously it has grown and how many flowers it has, which will grow again year after year. Unfortunately I forgot about it after planting and the stem flopped over, so must make a note to stake it next year!